Check Engine Light: What To Do

Check Engine Light On--What Do I Check
This light title is a bit of a misnomer. Sometimes the light says "service engine soon" and sometimes it's just an outline of an engine. The technical name is Malfunction Indicator Light or MIL. The light is indicating that the engine computer has detected a fault in the system. The computer uses a number of sensors to monitor and control what is happening with the engine and perhaps a few other systems in the car. In most cases, a scanner is used to hookup to the computer thru an on-board diagnostic port, usually under the dash by the driver's knees.
Here is the connector for this car. Sometimes there is a little door below the instrument panel or steering wheel that you have to open to get to the port. If you don't see it by the driver's knees, check behind the glovebox and also in the engine compartment near the relay box. It may be that your car is too old to have an OBD II connector (OBD II became a standard in 1996). Google OBD II port and your car model/year to see if you have a port and how to access it. In some cases, there are procedures to extract the trouble codes without a scanner, especially prior to 1996. Also, many cars older than 1996 may have an OBD I port. These systems may also be scanned, but the data may be less useful in many cases.
The scanner will read the fault codes stored by the computer. Many parts chains, such as Autozone, Advance, O'Reilly, or Pep Boys will provide a free scan of your car/truck. You can also buy a Bluetooth interface these days for about $20 that you can use with a free smartphone app to scan your computer or you can buy a simple scanner for about $25. I have one in my car at all times, and I have them in my wife’s and daughter’s cars as well. I have a more expensive scanner that can also scan anti-lock brake systems and transmission control modules. My scanner can also be used to view the snapshot of data it collected when it lit the MIL and to view live data. The live data can be used to troubleshoot a lot of sensors, such as the mass airflow, oxygen, throttle position, accelerator position, and fuel pressure. Your dealer may have a more advanced scanner that can troubleshoot each code down to the component; but, if you want to do it yourself, write down the codes and look them up online. The following page lists the standard codes and their probable causes:
www.obd-codes.com/trouble_codes/. In addition to these standard codes, many cars have special codes or a different diagnostic system. If your codes do not match those in the above link, look online for a special set of codes for your vehicle.
If your check engine light comes on while driving, you may be able to continue driving as long as the car is not having any symptoms, but you should check the trouble codes as soon as possible. Click the following link to see my emergency guide to trouble codes to help you decide whether or not to stop driving the car or to continue on your trip:
byteyourself.byethost7.com/Can...
If the engine light is blinking, I would not drive the car except in an emergency. There is likely a serious problem that could damage the engine, and it’s likely that the computer has put the engine into limp mode. Limp mode is a way to allow the engine to run but to limit the RPMs and power it produces. It is intended to allow you to reach a safe place before stopping the vehicle for towing or repair.
The codes and causes only give you some ideas for troubleshooting. I have made some videos to explain how to troubleshoot some trouble codes, but you need to have information specific to your vehicle to troubleshoot most codes. That is why it’s best that I end this video here. Please enjoy the rest of your day.