Awesome video! I’ve had a scanner for a while but never understood what exactly to look for as far as live data in diagnosing my problem. Thank you for your time!
Great video's on live data. I'm new to reading live data and I need some guidance on how to diagnose a high-idle condition on a 2005 Corolla. Idle is around 1,000 RPM and is a quite rough so I assumed a vacuum leak, but I've checked/changed all vacuum hoses and even replaced the MAF sensor and confirmed no manifold or PCV leaks. Since the car is 18 years old (original owner), I've replaced both O2 sensors and all injectors which improved the vibration level, but it is still present. The last thing I did to the car was to clean out the throttle body (there is no IAC valve). Here are some live-date anomalies (at operating temp) after my last repair: SHRTFT = -20.3% (LONG is 5.5%), TP = 14.9% and will not go to zero even though the adjustment is full minimum, O2S11 = 2.914V (S12 is .095V). Do you have any idea what may be causing the rough, high idle?
Cold air intake will gain power. A lot of factory ecu are calibrated to be a little richer at wide open throttle, adding the cold air intake leans it out a little and gain power. Closed loop is only used during idle and cruising.
I hate invisible vacuum leaks, high fuel trim s both short and long so here I go today, wish me luck. I have to see if my egr is stuck open a little first.
Incredibly informative material here, brother! First-class all the way! I have been watching videos and clips trying to learn how to read live data for 20+ years still not quite understanding it all. In 14 min you just topped all of the others! Wow! Thank you sir. Outstanding!
I'd just like to add... In my case, I was getting the 171/174 codes. So instantly thought lean/vacuum issue. So, took a water bottle, and sprayed along the intake manifold along both sides, and sure enough, got the engine to stumble. Replaced the intake gasket, and hooked up the scanner, and during the drive cycle, it thru the check engine light again, with the 174 code. Hooked up a smoke tester, found a cut gasket on the Throttle Body. Then had the smoke tester at 5psi, and saw no visible leaks anywhere, while holding 5psi for several minutes. Reset the computer, and started the drive cycle again. Was watching the fuel trims again, and the long terms kept going higher and higher, and were staying in the 12-15% range through various road conditions, stop/go traffic, up and down hills etc. Then as I was thinking the drive cycle should be completed, it threw the 174 code, AGAIN. So, now I had to change my thinking from "too much air" causing the lean codes, to "not enough fuel"... Because I know there are no vacuum leaks, it has to be on the fuel side. Either clogged fuel filter, kinked fuel line, bad fuel pump etc. So, just wanted to add, that LEAN doesn't always mean "vacuum leak".. it can sometimes mean "not enough fuel"
2016 Sonata Hybrid 151k miles Idling in Maint mode after 20 mile drive Smooth idle No power loss No mpg loss No rotten egg smell Some lifter noise at slow speed, light accelerator, uphill before gearing down. P0420 New 02 sensor on Bank1 S1 (cat is in manifold) Sensor 2 (in front of lower cat) is factory. Any ideas would be greatly appreciated. 👍 STFT 15.6% LTFT -32.0 02S12 (V) = .790 V 02S11 (mA) 0 to -.05 STSO2FT1 -1.6% LGSO2FT1 3.1% CATTEMP11 (576 Celsius) CATTEMP12 (400 Celsius) LAMBDA11 0.998 ish LAMBDA 0.999 ish
Hi thanks for sharing this information because I just bought A scanner obd2 reader for DIY for my ford escape 2004 I was viewing few on utube I just randomly clicked on your videos on how to read what is On the live data on fuel trims & short/ long term work Stogether with o2sensors l have learnt what is happening to my engine efficiency with your calm voice instructions I analyze with better clarity how to diagnose if having problems like vacuum leak all types etc or with fuel related issues so you emphasize things it’s simple but so important to learn I appreciate your help to me & other people search for answers by your videos bring it together for me any way thank you 👍😊 so I subscribe & like as well. Great job 🤙🏽
Fuel trims somtimes are not accurate, caused by one the sensors, like mine the MAP sensor cause both fuel trim to be at 12 to 14 percent, i tought i have vacuum leak, but it was the aftemarket delphi MAP senosr reporting wrong values to the ECM, i just put back the OEM sensor and the fuel trim went down to 5 percent. I couldnt believe it, the initiale issue was rought idling and somtimes engine misfire, but it was the ignition electric connection wires were loose at the aftermarket start button system, basically i create the problem overtime by using bad quickdisconnect connector, i replace the connector and problem solved partially rought idle and misfire, but fuel trim problem got fixed by installing OEM MAP sensor back.
Thanks for the information, I'm no mechanic, trying to fix an Issue I'm having with my Acura TSX 2009, it's giving me error code P0131, changed the spark-plugs, ignition. coils and even fuel injectors, but problem didn't go away. Car doesn't go over 20 mph ad checkengine is blinking. I got Foxwell scanner recently, but not sure what numbers I should be looking for when in comes to O2! SHRTFT1: -31.3, LONGFT1: -3.9, SHRTFTB1S2: -31:3
Great video. I have a vehicle that reads: O2 B1S1 .9mv O2 B1S2 .0mv O2 B2S1 .0mv O2 B2S2 1.0mv STFT bank 1 -20% STFT bank 2 30% LTFT bank 1 -4% LTFT bank 2 30% Inj. duty bank 1 4.4msec Inj. duty bank 2 11.5msec
Thank you. Very informative. My LT Trim is -25% and my buddies got me tracking down a phantom vacuum leak. Now I'm gonna pressure test the fuel system to look for a leaking injector
Love this video and thank you I found my knock sensor that was in my truck but I like the cold air because it makes my car sound good but you are right it doesn't gain any horsepower this is a great video thank you
I have a 2014 Jeep JK that has had a small engine surge while going down road. At idle, not detected. Least surge is not detected on tach, the up/down is so quick, really doesn’t have time to register. Worst cases, while going up a hill around 35-40mph, by ear it is swinging much more and you can see on tach that it is 50-75 rpm fluctuations. No codes at all. Looking at o2 sensors and fuel trims after engine is in op temp but at idle, o2 upstreams are bouncing all over 75mv up to 800+. Again it is so quick, can not grab a solid number. Downstream sensors however, b1s2 sits around 250mv while b2s2 is around 685mv. While these o2 readings are taking place, fuel trims stftb1, stftb2 and ltftb2 are bouncing between .0 and -3.9. Ltftb1 sits at 0, no movement. It will change when revved up, but still not hanging near where the others are going. Could b1s2 o2 sensor be going out? Could that cause my surge? Shops I have taken it to say no code, no problem without looking at it to see what I’m hearing and seeing. 84k miles on engine and first issues I’ve had. Owned since new.
Basically, yes. Vacuum leaks tend to be persistent, and that likely shows up as positive on LTFT: you'll see that fade to a lower number as throttle body opens most cases, but STFT picks up first. If fuel pressure is to high, or injector metering more than designed [for whatever reason] trim shows up negative. STFT is more of a fine tuning/rapid response - it should be active, as temperatures and manifold air pressure vary during operation, and sensors provide feedback to ECU. LTFT keeps you in workable mixture range [steady state] to allow STFT to nail down air/fuel ratio [changing speeds].
Awesome, was looking at the live data the other day for a p0141 on a rav4, and you are correct not a lot of good content exists, so thank you and keep'em coming:)
I had a p0160 b2s2 . I put my scanner on the live data and it was like a constant value. Then I rev the engine a little and then I saw it change some. I ended up jus clearing code since I saw the reading change some after rev the engine some. I had the car idleing some for awhile so as I was working on something dealing with the power steering fluid flush(suck fluid and add 3 times) I’ll keep my eye on this one p0160. B2s2. Great vid on this subject matter
Should I be checking theses while idling? My truck seems to be having issues when I am towing and going up hill. No codes, no misfires, took to shop for a trans flush. Dropped pan, all looked good. No metal in pan and fluid wasn’t that dirty. When I punch it, I can feel and hear that my truck is not shifting like it used to, and when I am towing up hill my truck will jump when I’m 1st or 2nd. Once I get pass 2Nd truck seems to run fine. So I have a OBD reader plugged in right now and I am trying to understand the terminology etc. so, when checking my O2 sensors and fuel trim, should I be checking while driving or in idle? Bc when I step on it, my % goes well over 10%. Hope all this makes sense. Thanks for your vids
I have a ford explorer right now where I have negative fuel trim on bank one and positive fuel trim on bank two. That's long term fuel trim. My short term is great. This truck came from another shop and I didn't get a straight story of what's been done.
I was looking at the reading on mine 02 sensor it's not responding and it's stuck on a number I looked at the graph flat line is that a bad O2 sensor it's causing backfires and a random misfire
9.4 fuel trim is a bit high.. 😅 I won't even tell you what mine was then lol I haven't got to figure out my p0171 lean code yet but I think it was because I didn't have an air filter on my cold air because it fit different on my 98 cobra, or i need to plumb the valve cover vent back into the crankcase for positive vacuum because the 98 was a little different that the 01 cobra but it was dumping about 25% on the trim. Luckily im still breaking in the motor so there was no getting in it with those trim levels.
These values while the car is not moving, idle, what happens when you step on the gas or open the throttle? How much should the short and long fule trim be???
It sure would be nice if these chinese manuals would elaborate what each of the readings mean past a simple expanded name when you push the ? mark key such as explained in this video. Thank you.
04 Jeep Liberty 3.7L, 115k got a P0157 bank 2 sensor 2 low voltage a couple weeks ago. Cleared code and hasn’t come back. It got me looking at live data and notice my long term fuel trims are at or around +10 all the time. I couldn’t find any vacuum leaks. My short terms seams close to zero. Little bit of rough idle, more rough when cold. Both cats replaced at 90k by previous owner. No other codes and the P0157 never came back. I don’t hear any exhaust leaks.
Thank You!! Very informative video.. but what about diagnosing faulty OSS or (Output Speed Sensor) on Transmission 4.6L? I've already wasted money replacing it with 3 different ones.. still having code, and engine light, and O/D light blinking!! Wires all seem to look fine.
Hi, one of my upstream sensors on my 2014 Ford Mustang is showing a negative value. My STFT for bank 1 is +34 and for bank 2 it's -25. Both long-term are 0. My vehicle is not running well. Rough idle, poor acceleration, bad gas mileage, sometime I smell the rotten egg/sulpher smell, etc. No check engine light. Please help. Thank you.
Thanks, watched video twice. So understand how its all goes together. ? My shortT reading -17. Longt 0.0 so how I'm understanding my issue is not vacuum leaks. Itd a fuel issue. . so my ? Is I have been putting fuel injector cleaner and its not that. So I'm gonna go with a fuel injector is clogged ? So I would have to basically clean all of them because I don't know what fuel injector is they don't label which one would be the one bad right? Thank you so much for your help. I so understand how it works. So what would I do next do I put maybe a direct cleaner to the fuel injectors or do I have to clean each one by hand which I don't even know how to do I'm going to touch them before and I'm a female mechanic for 25 yes. You and wiring electrical was not my thing though I so confused with injectors does this but if you could like give me a little push or something what should I look for I mean what should I do for the injectors and if it doesn't clear up see my fuel pump was a new fuel pump was put in like I want to say maybe a year and a half ago. I'm leaning more towards of fuel injector clogged I think thank you again have a great night
It sounds like you are saying the cold air intake, bigger intake air hose, or bigger throttle body does not make a difference since the ECU will simply adjust (eg keep the throttle body more closed) to compensate/restrict the extra air intake to keep the same 14.7:1 air to fuel ratio. Correct?
what does it mean if both my o2b1s1 and o2b1s2 go to a steady 0.20 (could be 0.020 i forget, but point is it's steady and will have pending code) when the fan or stereo is on? when i turn both off, those sensors seem to fluctuate again. also, are the o2 sensors supposed to go to steady value like i mentioned in park? all my o2 sensors (2 banks 2 sensors each) drop to a steady 0.20 or 0.40 in park. or is that a function of not being in closed loop like you mentioned, because i didnt let my bank 1 sensors run long enough (because of the stereo or fan being on)?
Greetings, I have a suzuki Kizashi 2.4L S. The ecu throws check engine light with p0101 code. The fault code is thrown under 3 conditions: 1. Coasting downhill with zero to minimim accelerator input. (Tps at 19.6 degree, MAF at 10-11g/sec) 2. Cold start after 24+hours in colder environment. Ltft drops down suddenly to -11 to -17% but goes back to 0-3% 3. High rpm idle test. Rpm set at 2.5k, stft increases from +1% to 5% and then returns back to 0%to1%. Can you suggest a way forward? I also have a bad valve cover gasket
Excellent Video... much appreciated. I have a 1996 E-150 5.8L EFi . Have ABS light on, OBD2 reader says "This vehicle does not support ABS communication" is that correct ? if so do you know of any other way to identify the faulty sensor (assuming it is a sensor fault) also..... when backing off the throttle the RPM holds, at whatever RPM you were at, for 2 - 3 seconds before dropping.... any ideas ? there is the occasional hickup at idle and sometime it stalls. PCV valve replaced. Any help would be much appreciated. Regards Paul
Best video in my opinion took time to explain everything and in laymen terms so a bigginer will understand my question is I noticed this on yours and mine off to side there is a question mark and G what do they mean if anything thanks and again video is the best
Hey, thanks for that man I appreciate it! I have new ones coming soon that go into a lot more detail as well! Some scanners are different but alot of times you can click the question mark and it will tell you more information. Yours may be different though. Thanks for watching!
Thanks for the great video. Helped a lot. I have a problem you didn't cover hoping you could answer for me. My STFT B1 S2 is 99.2 and my STFT B1S1 is - 63. If you could tell me what that is. And what's causing the 99.2. It never changes it like it is stuck. Thanks
Just seeing this sorry, I hope you got it figured out. 9 times out of 10 a maxed out fuel trim (99%) is caused by a bad 02 sensor. See what they're reading. Alot of times when you see the fuel trim at 99 you'll have an 02 sensor not really reading much, no change or super laggy and barely moving at all. Again sorry for the late response.
I have a 2004 liberty 3.7 I got two codes, p0132 and p0152 every thing from the pcm to the connectors is okay, I checked resistance in every cable and all are okay, I changed both o2 upstream sensors oem, and still the same keep steady Reading of 1.270 on both o2 Sensors, down stream sensors Reading are weird also, I got 0.035 on both sides sometimes they go up to 0.700 and sometimes the upstreams start to oscilate but for a few seconds. Do you know what can be causing this?
got a 09 qx56 infinity, longft1 -3.9 shortft1 -3.9 longft2 -7.0 shorth ft2 3.1 02B1S1 2.47 02B3S1 2.255 02B3S2 0.080 02B1S2 0.050, getting p 0420 code, change bank1 sensor 2 and MAF sensor, CEL stayed off for a day and back on now. took off exhaust bolts and was told CAT looks fine, any advise.
Got P0171 lean bank 1 on 03 S10 2.2 engine , LTFT at 1100 rpm 21.9. STFT 3.1. No vacuum leaks , would you have any ideas ? Thanks , I have 18lbs of vacuum at idle
Great info. Thank you. But one observation if you don't mind. 10:25 Isn't spraying "soapy water" on the intake leak sucking it into the engine? I'm no mechanic, but I think that's bad.
I have 1500cc petrol engine in toyota ...... I tried two maf sensor one giving 1.3 g/s at 650 rpm.... Another giving 1.7 g/s at 650 rpm.... Which one should i use for better fuel economy.....plz reply
Thank you for the information, I have a Toyota corolla LE 2012 and I failed the smog test because of 02 sensor and cat but my car did not show any code also I follow a Toyota drive cycle and I drove 360miles highway 55 t0 60 after I slow down without using break just helping the car with hand break to 35-45 but still not ready! but when I plugged my OBD2 IT SHOW THAT MY O2S1 bank1 (V)=3.306 AND O2S1BANK2 (V)= 0.660 the car was warmed up for more than 10 min ! please do I need to change both 02 and after drive it probably it will make the car ready for emission! thank you very much
Hi how are things ? I have a 2011 Mazdaspeed 3 2.3L Turbocharged with Rich's issues I have the long term fuel trim at sometimes -16, -19,- 17, as the car warms up it becomes more negative, speeding up the long term fuel trim fuel trims, it goes down to -9.50 or sometimes -10.50 could the problem be a vacuum leak, or air leak after the MAF sensor? the short terms always go 0 -0 sometimes +7 but when accelerating sharply sometimes it jumps to crazy numbers like -17 or sometimes +20 what could be the problem friend? I would like to hear the comment
I have a 2001 chevy prizm 1.8 toyota vvt , (no i or 4 , different engines). Should the readings be the same where the O2 sensors or air/ fuel sensor and fuel trim readings are concerned? Thanks. J.
I’m getting a positive ltft reading only on bank 2 I’ve checked and changed almost everything including catalyst converter and still no change sprayed brake clean around the intake as well
What if you drive a Ford and no O2 sensor voltage can be displayed? My bi directional tool can only display microamps on the downstream sensor, which is meaningless to me. I CAN see voltage on my GM and Chrysler vehicles. Does Ford use a different data point at the ECU to adjust fueling?
Thank you for the video I picked up A lot of knowledge I have a 2006 Audi S4 4.2 and the problem I’ve been having is with the long term fuel trim bank one is usually lower than bank two sometimes bank one goes up to 8 to 9 on positive as bank two stays around eight and then shoots up to 12 my mechanic and I have looked at everything we didn’t fine no leaks through the intake , maf or any of the vacuum lines and then every 6 to 7 days I get P0492 P0171 and P0174 lean codes what do you recommend will be the next thing to check for go to be maybe I have bad O2 sensors or could it be coming from the exhaust I’m so frustrated trying to find the problem of this issue also I get a little rough idle on standstill as well other than that the car runs great on highway and on full speed. Please let me know your input would be very valuable Also forgot to mention 02 oxygen sensor on bank two reads 0.00 doesn’t move
Hey. Superb video. I have strange problem with short fuel trims. My engine is BMW M54B30. On bank 1 i got +25-28%, but on bank 2 it is ok 0 to 5%. I know that my oxygen sensor after cat on bank1 is dead. Is this can affect on fuel trims? MAF is working, I checked rubber hoses and there is no cracks. Help please. Thanks.
Got negative ten long term fuel trims a touch higher on bank 1...a bit low o2 sensor readings on upstream...Maf reading at about 4.3...2001 nissan sentra gxe with the 1.8...runs pretty good but a little rough on the idle...cleaned throttle body and iac...experimented with the egr...any ideas?
I changed my plugs, ignition coils and fuel injectors on my ford e-350 6.8 v-10 because I was getting engine miss fire codes and I kept getting the codes after I changed the plugs, so I went ahead and changed the coils and injectors. That solved the miss fires but now it won't pass smog and the other day I noticed I got a rich fuel code on bank 2. The upstream o2 sensor voltage fluctuates between .100-.800 volts on the bank 2 side of the exhaust but the o2 sensor voltage on the bank 1 side stays steady at around .900. which. My question is which o2 sensor is working properly the one staying at a steady voltage or the one that's fluctuating?
also to add to my question if one of my upstream o2 sensors i find is not working properly could that be the cause of the rich fuel code and it failing the smog test. They say it's coming up as a gross polluter mainly on the idle speed test. The higher rpm test also fails but not gross polluter
Hi, I hope you’re still checking your channel. I have a question on data stream codes. What does it mean when my oxygen sensor codes give me N/A instead of a number. (O2B1S1 N/A) I have a reading for B1S2 but then not B2S1, B2S2, B3S2, B4S1 (all have N/A). BTW thank you for these videos. Could you do more on all these other codes? SPARKADV, MAF, etc
In an older car, like a 2000, does the ECU use the downstream sensor for fuel at all? I've heard differing opinions, but most people say the secondary O2 sensor after the cat is just there to determine the health of the cat, and only the primary O2 sensor decides the fuel. I put an 02 sensor spacer in mine to get rid of the P0420 and am wondering if that's messing with my fuel trims at all.
That second o2 sensor is there for correcting air fuel ratio, not health of your cat. Some people put the spacer in to trick the ecm when a bad cat is present. It may very well be your issue.
Thanks for the video. I ran the OBD on my car, monitored values real time and found that my bank 1 sensor 1 and bank 2, sensor 1 are showing values between 4% and -4%. However, bank 1 sensor 2 and bank 2 sensor 2 are both stuck at 99.22%. Getting P2096 code after I got the shop to install the complete catback solo exhaust. What's your take on this? Can't be the sensors going bad. I am assuming they didnt plug it in properly etc....
Easily the best video on o2s and trim I've seen.
No BS
Straight up knowledge.
Excellent video.
Thank you
Awesome video! I’ve had a scanner for a while but never understood what exactly to look for as far as live data in diagnosing my problem. Thank you for your time!
Exelent explanation on how this o2 sensors work. It might take me 20 times to see this video but you went really well.. Thank you 👍🏻
Thank you for teaching me how to read my sensors, you are a life saver. Awesome video.
Very educational.. I'm a diy person and bought a Zurich z8.. now I understand these readings better.
Great video's on live data. I'm new to reading live data and I need some guidance on how to diagnose a high-idle condition on a 2005 Corolla. Idle is around 1,000 RPM and is a quite rough so I assumed a vacuum leak, but I've checked/changed all vacuum hoses and even replaced the MAF sensor and confirmed no manifold or PCV leaks. Since the car is 18 years old (original owner), I've replaced both O2 sensors and all injectors which improved the vibration level, but it is still present. The last thing I did to the car was to clean out the throttle body (there is no IAC valve). Here are some live-date anomalies (at operating temp) after my last repair: SHRTFT = -20.3% (LONG is 5.5%), TP = 14.9% and will not go to zero even though the adjustment is full minimum, O2S11 = 2.914V (S12 is .095V). Do you have any idea what may be causing the rough, high idle?
Smoke test
Cold air intake will gain power. A lot of factory ecu are calibrated to be a little richer at wide open throttle, adding the cold air intake leans it out a little and gain power. Closed loop is only used during idle and cruising.
Very useful brother. I'm working in NISSAN dealer in Dubai. It's much helpful for me.
I hate invisible vacuum leaks, high fuel trim s both short and long so here I go today, wish me luck. I have to see if my egr is stuck open a little first.
Incredibly informative material here, brother! First-class all the way! I have been watching videos and clips trying to learn how to read live data for 20+ years still not quite understanding it all. In 14 min you just topped all of the others! Wow! Thank you sir. Outstanding!
I'd just like to add...
In my case, I was getting the 171/174 codes. So instantly thought lean/vacuum issue.
So, took a water bottle, and sprayed along the intake manifold along both sides, and sure enough, got the engine to stumble.
Replaced the intake gasket, and hooked up the scanner, and during the drive cycle, it thru the check engine light again, with the 174 code.
Hooked up a smoke tester, found a cut gasket on the Throttle Body.
Then had the smoke tester at 5psi, and saw no visible leaks anywhere, while holding 5psi for several minutes.
Reset the computer, and started the drive cycle again.
Was watching the fuel trims again, and the long terms kept going higher and higher, and were staying in the 12-15% range through various road conditions, stop/go traffic, up and down hills etc. Then as I was thinking the drive cycle should be completed, it threw the 174 code, AGAIN.
So, now I had to change my thinking from "too much air" causing the lean codes, to "not enough fuel"... Because I know there are no vacuum leaks, it has to be on the fuel side. Either clogged fuel filter, kinked fuel line, bad fuel pump etc.
So, just wanted to add, that LEAN doesn't always mean "vacuum leak".. it can sometimes mean "not enough fuel"
interesting hypothesis
Thank you sir. I am having about 28 positive at longtrim. I will check for a air leaking somewhere .
2016 Sonata Hybrid 151k miles
Idling in Maint mode after 20 mile drive
Smooth idle
No power loss
No mpg loss
No rotten egg smell
Some lifter noise at slow speed, light accelerator, uphill before gearing down.
P0420
New 02 sensor on Bank1 S1 (cat is in manifold)
Sensor 2 (in front of lower cat) is factory.
Any ideas would be greatly appreciated. 👍
STFT 15.6%
LTFT -32.0
02S12 (V) = .790 V
02S11 (mA) 0 to -.05
STSO2FT1 -1.6%
LGSO2FT1 3.1%
CATTEMP11 (576 Celsius)
CATTEMP12 (400 Celsius)
LAMBDA11 0.998 ish
LAMBDA 0.999 ish
Learning to read my scanner and was wondering what some of the terms and readings were all about, and wow, I found your very informative comments
WoW hat's off sir what a great and deep and easy lecture with live data streaming salute sir
Hi thanks for sharing this information because I just bought A scanner obd2 reader for DIY for my ford escape 2004 I was viewing few on utube I just randomly clicked on your videos on how to read what is On the live data on fuel trims & short/ long term work Stogether with o2sensors l have learnt what is happening to my engine efficiency with your calm voice instructions I analyze with better clarity how to diagnose if having problems like vacuum leak all types etc or with fuel related issues so you emphasize things it’s simple but so important to learn I appreciate your help to me & other people search for answers by your videos bring it together for me any way thank you 👍😊 so I subscribe & like as well. Great job 🤙🏽
One hell of an informative video.
Fuel trims somtimes are not accurate, caused by one the sensors, like mine the MAP sensor cause both fuel trim to be at 12 to 14 percent, i tought i have vacuum leak, but it was the aftemarket delphi MAP senosr reporting wrong values to the ECM, i just put back the OEM sensor and the fuel trim went down to 5 percent. I couldnt believe it, the initiale issue was rought idling and somtimes engine misfire, but it was the ignition electric connection wires were loose at the aftermarket start button system, basically i create the problem overtime by using bad quickdisconnect connector, i replace the connector and problem solved partially rought idle and misfire, but fuel trim problem got fixed by installing OEM MAP sensor back.
Thanks for the information, I'm no mechanic, trying to fix an Issue I'm having with my Acura TSX 2009, it's giving me error code P0131, changed the spark-plugs, ignition. coils and even fuel injectors, but problem didn't go away. Car doesn't go over 20 mph ad checkengine is blinking. I got Foxwell scanner recently, but not sure what numbers I should be looking for when in comes to O2!
SHRTFT1: -31.3, LONGFT1: -3.9, SHRTFTB1S2: -31:3
The point you made about the cold air is true. If you change the air fuel ratio outside of factory you'll need a tune.
i'm starting to understand this whole thing.Thanks man
And that’s why the screen has all that info; makes it easy to understand.
Love the explanation. My Camry stft 0.0. And ltft 38.9. I change maf and 02 sensors also done smoke test
Great video. I have a vehicle that reads:
O2 B1S1 .9mv
O2 B1S2 .0mv
O2 B2S1 .0mv
O2 B2S2 1.0mv
STFT bank 1 -20%
STFT bank 2 30%
LTFT bank 1 -4%
LTFT bank 2 30%
Inj. duty bank 1 4.4msec
Inj. duty bank 2 11.5msec
The zeros should be replaced right
It’s very good explanation video, Make me more understanding about the STFT and LTFT Thank you
Thank you. Very informative. My LT Trim is -25% and my buddies got me tracking down a phantom vacuum leak. Now I'm gonna pressure test the fuel system to look for a leaking injector
Mark Dziamski hey did u find the problem minds is -3.1
@@jarademajor8401 -3.1 is perfectly normal !
one of my short terms is + 25
Sounds like you got a stuck open injector.
Your buddies are exactly wrong. -25 means the mixture is extremely rich. That's not a vacuum leak. It is the exact opposite.
Good video bro. I've been twisting wrenches for yrs,but I needed to understand my live data.👍
Love this video and thank you I found my knock sensor that was in my truck but I like the cold air because it makes my car sound good but you are right it doesn't gain any horsepower this is a great video thank you
I have a 2014 Jeep JK that has had a small engine surge while going down road. At idle, not detected. Least surge is not detected on tach, the up/down is so quick, really doesn’t have time to register. Worst cases, while going up a hill around 35-40mph, by ear it is swinging much more and you can see on tach that it is 50-75 rpm fluctuations. No codes at all. Looking at o2 sensors and fuel trims after engine is in op temp but at idle, o2 upstreams are bouncing all over 75mv up to 800+. Again it is so quick, can not grab a solid number. Downstream sensors however, b1s2 sits around 250mv while b2s2 is around 685mv. While these o2 readings are taking place, fuel trims stftb1, stftb2 and ltftb2 are bouncing between .0 and -3.9. Ltftb1 sits at 0, no movement. It will change when revved up, but still not hanging near where the others are going. Could b1s2 o2 sensor be going out? Could that cause my surge? Shops I have taken it to say no code, no problem without looking at it to see what I’m hearing and seeing. 84k miles on engine and first issues I’ve had. Owned since new.
13:00
STFT POSITIVE adding fuel ~>Vacuum leaks
STFT NEGATIVE taking fuel away ~>Fuel system issues (injectors or fuel pressure regulator) Correct???
Not necessarily. Positive and negative will 0 out +5 short and -5 long means 0
Basically, yes. Vacuum leaks tend to be persistent, and that likely shows up as positive on LTFT: you'll see that fade to a lower number as throttle body opens most cases, but STFT picks up first. If fuel pressure is to high, or injector metering more than designed [for whatever reason] trim shows up negative. STFT is more of a fine tuning/rapid response - it should be active, as temperatures and manifold air pressure vary during operation, and sensors provide feedback to ECU. LTFT keeps you in workable mixture range [steady state] to allow STFT to nail down air/fuel ratio [changing speeds].
Awesome, was looking at the live data the other day for a p0141 on a rav4, and you are correct not a lot of good content exists, so thank you and keep'em coming:)
I had the phone plugged into the truck stereo not as noticeable through the phone and laptop. Another good video.
Bob Wolf thank you I appreciate that!
Perfect, the way you explain 👌👌👌👌👌
All the way from south africa
This is an incredible video !!! Amazing explanation on live data
I had a p0160 b2s2 . I put my scanner on the live data and it was like a constant value. Then I rev the engine a little and then I saw it change some.
I ended up jus clearing code since I saw the reading change some after rev the engine some. I had the car idleing some for awhile so as I was working on something dealing with the power steering fluid flush(suck fluid and add 3 times)
I’ll keep my eye on this one p0160. B2s2. Great vid on this subject matter
2001 Toyota Camry 2.2 le , o2 b1s1>>>> 3.25. +/ - 02b1s2>>>>0.050. What is o2b1s1 reading mean ? Your video is very very informative thanks
Should I be checking theses while idling? My truck seems to be having issues when I am towing and going up hill. No codes, no misfires, took to shop for a trans flush. Dropped pan, all looked good. No metal in pan and fluid wasn’t that dirty. When I punch it, I can feel and hear that my truck is not shifting like it used to, and when I am towing up hill my truck will jump when I’m 1st or 2nd. Once I get pass 2Nd truck seems to run fine. So I have a OBD reader plugged in right now and I am trying to understand the terminology etc. so, when checking my O2 sensors and fuel trim, should I be checking while driving or in idle? Bc when I step on it, my % goes well over 10%. Hope all this makes sense. Thanks for your vids
Thanks for making this video. It helps me a lot. What numbers patterns indicate O2 sensor is bad? Like, number not moving like your sensor 2?
I have a ford explorer right now where I have negative fuel trim on bank one and positive fuel trim on bank two. That's long term fuel trim. My short term is great. This truck came from another shop and I didn't get a straight story of what's been done.
Real good explanation of FT.
Your doing a good job keeping us informed thank you
I was looking at the reading on mine 02 sensor it's not responding and it's stuck on a number I looked at the graph flat line is that a bad O2 sensor it's causing backfires and a random misfire
9.4 fuel trim is a bit high.. 😅
I won't even tell you what mine was then lol
I haven't got to figure out my p0171 lean code yet but I think it was because I didn't have an air filter on my cold air because it fit different on my 98 cobra, or i need to plumb the valve cover vent back into the crankcase for positive vacuum because the 98 was a little different that the 01 cobra but it was dumping about 25% on the trim.
Luckily im still breaking in the motor so there was no getting in it with those trim levels.
Great video bro, good way to explain everything in easy terms to understand
You do well on explaining as well diagnosis
Knowledge is great for self taught good job
These values while the car is not moving, idle, what happens when you step on the gas or open the throttle? How much should the short and long fule trim be???
Thank you for ur video I’m new on this subject and new on using a scan tool I appreciate your information and how u cover the information thanks
Thanks man for clarifying these readings, so useful!!
Great video!!! Very explanatory! So I been dealing with an issue where my cat fuel trims aren't moving and my bank 1 sensor 1 is reading no voltage
It sure would be nice if these chinese manuals would elaborate what each of the readings mean past a simple expanded name when you push the ? mark key such as explained in this video. Thank you.
04 Jeep Liberty 3.7L, 115k got a P0157 bank 2 sensor 2 low voltage a couple weeks ago. Cleared code and hasn’t come back. It got me looking at live data and notice my long term fuel trims are at or around +10 all the time. I couldn’t find any vacuum leaks. My short terms seams close to zero. Little bit of rough idle, more rough when cold. Both cats replaced at 90k by previous owner. No other codes and the P0157 never came back. I don’t hear any exhaust leaks.
Thank You!! Very informative video.. but what about diagnosing faulty OSS or (Output Speed Sensor) on Transmission 4.6L? I've already wasted money replacing it with 3 different ones.. still having code, and engine light, and O/D light blinking!! Wires all seem to look fine.
Hi, so good video! My understanding for videos before is that the sensor 2 downstream is not ok and can also be catalysator
Hi, one of my upstream sensors on my 2014 Ford Mustang is showing a negative value. My STFT for bank 1 is +34 and for bank 2 it's -25. Both long-term are 0. My vehicle is not running well. Rough idle, poor acceleration, bad gas mileage, sometime I smell the rotten egg/sulpher smell, etc. No check engine light. Please help. Thank you.
Now I finally got a little understanding about this. Thank you..
Good job. Others start with the wheels and after a while get to the fuel.
Thanks, watched video twice. So understand how its all goes together. ? My shortT reading -17. Longt 0.0 so how I'm understanding my issue is not vacuum leaks. Itd a fuel issue. . so my ? Is I have been putting fuel injector cleaner and its not that. So I'm gonna go with a fuel injector is clogged ? So I would have to basically clean all of them because I don't know what fuel injector is they don't label which one would be the one bad right?
Thank you so much for your help. I so understand how it works. So what would I do next do I put maybe a direct cleaner to the fuel injectors or do I have to clean each one by hand which I don't even know how to do I'm going to touch them before and I'm a female mechanic for 25 yes. You and wiring electrical was not my thing though I so confused with injectors does this but if you could like give me a little push or something what should I look for I mean what should I do for the injectors and if it doesn't clear up see my fuel pump was a new fuel pump was put in like I want to say maybe a year and a half ago. I'm leaning more towards of fuel injector clogged I think thank you again have a great night
I use obd2 on my toyota vios 2004. The o2 sensor is one "Percent" not "volt". Please help.. is there nornal percentage for o2 sensor? Thank you.
It sounds like you are saying the cold air intake, bigger intake air hose, or bigger throttle body does not make a difference since the ECU will simply adjust (eg keep the throttle body more closed) to compensate/restrict the extra air intake to keep the same 14.7:1 air to fuel ratio. Correct?
what does it mean if both my o2b1s1 and o2b1s2 go to a steady 0.20 (could be 0.020 i forget, but point is it's steady and will have pending code) when the fan or stereo is on? when i turn both off, those sensors seem to fluctuate again.
also, are the o2 sensors supposed to go to steady value like i mentioned in park? all my o2 sensors (2 banks 2 sensors each) drop to a steady 0.20 or 0.40 in park. or is that a function of not being in closed loop like you mentioned, because i didnt let my bank 1 sensors run long enough (because of the stereo or fan being on)?
Hi, my O2 value Is at 0.75, and does not increase or decrease when car is revved, does this mean my O2 sensor is faulty ?
How did you see soapy bubbles from outside of a vacuum?
On a cold start, does the oxygen sensor post cat heater command need to be at 100% or its okay to have a a 10% value ?
Greetings, I have a suzuki Kizashi 2.4L S.
The ecu throws check engine light with p0101 code.
The fault code is thrown under 3 conditions:
1. Coasting downhill with zero to minimim accelerator input. (Tps at 19.6 degree, MAF at 10-11g/sec)
2. Cold start after 24+hours in colder environment. Ltft drops down suddenly to -11 to -17% but goes back to 0-3%
3. High rpm idle test. Rpm set at 2.5k, stft increases from +1% to 5% and then returns back to 0%to1%.
Can you suggest a way forward? I also have a bad valve cover gasket
Excellent Video... much appreciated. I have a 1996 E-150 5.8L EFi . Have ABS light on, OBD2 reader says "This vehicle does not support ABS communication" is that correct ? if so do you know of any other way to identify the faulty sensor (assuming it is a sensor fault) also..... when backing off the throttle the RPM holds, at whatever RPM you were at, for 2 - 3 seconds before dropping.... any ideas ? there is the occasional hickup at idle and sometime it stalls. PCV valve replaced. Any help would be much appreciated. Regards Paul
Best video in my opinion took time to explain everything and in laymen terms so a bigginer will understand my question is I noticed this on yours and mine off to side there is a question mark and G what do they mean if anything thanks and again video is the best
Hey, thanks for that man I appreciate it! I have new ones coming soon that go into a lot more detail as well! Some scanners are different but alot of times you can click the question mark and it will tell you more information. Yours may be different though. Thanks for watching!
You're a great teacher lets get this guy more subscribers
Hey man I seriously appreciate that! More videos coming very soon!
Exactly now IM a mechanic cause of trying . If you don’t try you never know
Excellent video. Thank you.
Best video.was waiting for the live data on the trims wave forms
Thanks for the great video. Helped a lot. I have a problem you didn't cover hoping you could answer for me. My STFT B1 S2 is 99.2 and my STFT B1S1 is - 63. If you could tell me what that is. And what's causing the 99.2. It never changes it like it is stuck. Thanks
Just seeing this sorry, I hope you got it figured out. 9 times out of 10 a maxed out fuel trim (99%) is caused by a bad 02 sensor. See what they're reading. Alot of times when you see the fuel trim at 99 you'll have an 02 sensor not really reading much, no change or super laggy and barely moving at all. Again sorry for the late response.
Bro..... great video. Please keep em coming. Best descriptive video ive seen in a long time
I have a 2004 liberty 3.7 I got two codes, p0132 and p0152 every thing from the pcm to the connectors is okay, I checked resistance in every cable and all are okay, I changed both o2 upstream sensors oem, and still the same keep steady Reading of 1.270 on both o2 Sensors, down stream sensors Reading are weird also, I got 0.035 on both sides sometimes they go up to 0.700 and sometimes the upstreams start to oscilate but for a few seconds. Do you know what can be causing this?
Just subscribed. Would be nice to see examples of what your explaining.
got a 09 qx56 infinity, longft1 -3.9 shortft1 -3.9 longft2 -7.0 shorth ft2 3.1 02B1S1 2.47 02B3S1 2.255 02B3S2 0.080 02B1S2 0.050, getting p 0420 code, change bank1 sensor 2 and MAF sensor, CEL stayed off for a day and back on now. took off exhaust bolts and was told CAT looks fine, any advise.
Got P0171 lean bank 1 on 03 S10 2.2 engine , LTFT at 1100 rpm 21.9. STFT 3.1. No vacuum leaks , would you have any ideas ? Thanks , I have 18lbs of vacuum at idle
Great info. Thank you. But one observation if you don't mind. 10:25 Isn't spraying "soapy water" on the intake leak sucking it into the engine? I'm no mechanic, but I think that's bad.
Propane
I have 1500cc petrol engine in toyota ......
I tried two maf sensor one giving 1.3 g/s at 650 rpm....
Another giving 1.7 g/s at 650 rpm....
Which one should i use for better fuel economy.....plz reply
Thank you for the information, I have a Toyota corolla LE 2012 and I failed the smog test because of 02 sensor and cat but my car did not show any code also I follow a Toyota drive cycle and I drove 360miles highway 55 t0 60 after I slow down without using break just helping the car with hand break to 35-45 but still not ready! but when I plugged my OBD2 IT SHOW THAT MY O2S1 bank1 (V)=3.306 AND O2S1BANK2 (V)= 0.660 the car was warmed up for more than 10 min ! please do I need to change both 02 and after drive it probably it will make the car ready for emission! thank you very much
Hi how are things ? I have a 2011 Mazdaspeed 3 2.3L Turbocharged with Rich's issues I have the long term fuel trim at sometimes -16, -19,- 17, as the car warms up it becomes more negative, speeding up the long term fuel trim fuel trims, it goes down to -9.50 or sometimes -10.50 could the problem be a vacuum leak, or air leak after the MAF sensor? the short terms always go 0 -0 sometimes +7 but when accelerating sharply sometimes it jumps to crazy numbers like -17 or sometimes +20 what could be the problem friend? I would like to hear the comment
Vacuum leak
What if my Longft1 and longft2 are the ones that are close to 0?
Very well explained great video help me out thank you
I have a 2001 chevy prizm 1.8 toyota vvt , (no i or 4 , different engines). Should the readings be the same where the O2 sensors or air/ fuel sensor and fuel trim readings are concerned? Thanks. J.
I’m getting a positive ltft reading only on bank 2 I’ve checked and changed almost everything including catalyst converter and still no change sprayed brake clean around the intake as well
The B1S1 and B2S1 sensors on my 2013 jx35 are reading 1.9-2.2v at idle and go up to 4v while coasting. Is that bad?
Yeah that sounds too high. It should fluctuate between 0 and 1 volt.
@@houlagan13 what do you think could be the problem?
What if you drive a Ford and no O2 sensor voltage can be displayed? My bi directional tool can only display microamps on the downstream sensor, which is meaningless to me. I CAN see voltage on my GM and Chrysler vehicles. Does Ford use a different data point at the ECU to adjust fueling?
Thank you for the video I picked up A lot of knowledge I have a 2006 Audi S4 4.2 and the problem I’ve been having is with the long term fuel trim bank one is usually lower than bank two sometimes bank one goes up to 8 to 9 on positive as bank two stays around eight and then shoots up to 12 my mechanic and I have looked at everything we didn’t fine no leaks through the intake , maf or any of the vacuum lines and then every 6 to 7 days I get P0492 P0171 and P0174 lean codes what do you recommend will be the next thing to check for go to be maybe I have bad O2 sensors or could it be coming from the exhaust I’m so frustrated trying to find the problem of this issue also I get a little rough idle on standstill as well other than that the car runs great on highway and on full speed. Please let me know your input would be very valuable Also forgot to mention 02 oxygen sensor on bank two reads 0.00 doesn’t move
Hey. Superb video. I have strange problem with short fuel trims. My engine is BMW M54B30. On bank 1 i got +25-28%, but on bank 2 it is ok 0 to 5%. I know that my oxygen sensor after cat on bank1 is dead. Is this can affect on fuel trims?
MAF is working, I checked rubber hoses and there is no cracks.
Help please. Thanks.
Got negative ten long term fuel trims a touch higher on bank 1...a bit low o2 sensor readings on upstream...Maf reading at about 4.3...2001 nissan sentra gxe with the 1.8...runs pretty good but a little rough on the idle...cleaned throttle body and iac...experimented with the egr...any ideas?
This is a very informative video
If O2B1S1(V) reading just only stays on negative, which parts is abnormal?
Mazda 3
What causes the fuel trims to be in negative
I changed my plugs, ignition coils and fuel injectors on my ford e-350 6.8 v-10 because I was getting engine miss fire codes and I kept getting the codes after I changed the plugs, so I went ahead and changed the coils and injectors. That solved the miss fires but now it won't pass smog and the other day I noticed I got a rich fuel code on bank 2. The upstream o2 sensor voltage fluctuates between .100-.800 volts on the bank 2 side of the exhaust but the o2 sensor voltage on the bank 1 side stays steady at around .900. which. My question is which o2 sensor is working properly the one staying at a steady voltage or the one that's fluctuating?
also to add to my question if one of my upstream o2 sensors i find is not working properly could that be the cause of the rich fuel code and it failing the smog test. They say it's coming up as a gross polluter mainly on the idle speed test. The higher rpm test also fails but not gross polluter
So the SHRTFT B2S1 at -1.6% is normal?
Hi, I hope you’re still checking your channel. I have a question on data stream codes. What does it mean when my oxygen sensor codes give me N/A instead of a number. (O2B1S1 N/A) I have a reading for B1S2 but then not B2S1, B2S2, B3S2, B4S1 (all have N/A). BTW thank you for these videos. Could you do more on all these other codes? SPARKADV, MAF, etc
02 connections?
So if you don't rev it up but the O2 jumps from lean to rich and throws c p0171 is that a bad sensor or just a vacuum leak somewhere
When I look at my o2 sensor graph my b1s1 shows .00 to .01 volts and the same with b1b2. When I give it gas the volts increase. Are these bad sensors?
In an older car, like a 2000, does the ECU use the downstream sensor for fuel at all? I've heard differing opinions, but most people say the secondary O2 sensor after the cat is just there to determine the health of the cat, and only the primary O2 sensor decides the fuel. I put an 02 sensor spacer in mine to get rid of the P0420 and am wondering if that's messing with my fuel trims at all.
That second o2 sensor is there for correcting air fuel ratio, not health of your cat. Some people put the spacer in to trick the ecm when a bad cat is present. It may very well be your issue.
Thanks for the video.
I ran the OBD on my car, monitored values real time and found that my bank 1 sensor 1 and bank 2, sensor 1 are showing values between 4% and -4%. However, bank 1 sensor 2 and bank 2 sensor 2 are both stuck at 99.22%. Getting P2096 code after I got the shop to install the complete catback solo exhaust. What's your take on this? Can't be the sensors going bad. I am assuming they didnt plug it in properly etc....
I had 2 o2 sensors that gave info that was badly interpretated by the car CPU mpg 13.5 rebooted the CPU Now mpg 19.5.
What's mean CPU buddy 🤔
I have a scanner reading on the sensor called Lambda Correction, and it shows a value between 3.5 and 5.0. Is this the same as STFT?