Check Engine Lights: Myths and Facts

You’re driving along and suddenly your Check Engine Light comes on. What does it mean? Check Engine Light, Check Engine Soon Light, Service Engine Soon Light, Engine Light, Engine Management Light, whatever you want to call it, simply means that your vehicle’s computer system has detected a problem. Depending on the year, make, and model, it may be related to the engine, the transmission, even the brakes and suspension. There are literally hundreds of reasons a Check Engine Light may appear. The following questions and answers discussion will clarify the truth about Check Engine Lights.
Service Engine Soon Light FAQ: Can the car be driven? The general rule is: if the Service Engine Soon Light is on, and the car seems to be running ok, you can drive it. However, you should have it checked at your earliest convenience.
If your vehicle is running poorly—bucking, stalling, hesitating, or you just don’t feel safe, tow it. When in doubt always tow it! The check engine light went out by itself. Is it ok now? Probably not. Check Engine Lights often come and go. Even if the light is out, your vehicle’s computer system will retain information that will allow the problem to be diagnosed. To avoid potential long term issues, get it checked out.
My check engine light stays on. What should I do? If your check engine light stays on constantly, follow the instructions above, under “Can the car be driven?” Don’t panic.
Can I disconnect the battery, or pull a fuse to reset the service engine soon light? Maybe, but I wouldn’t. Removing the battery cable or an ECM or PCM fuse may clear the code, but it is not universally recommended in the industry. Most manufacturers advise against it. See the Best Way to Reset Check Engine Light Codes below.
What is the Check Engine Light? The Check Engine Light is a warning light for multiple systems operating in your vehicle. In simplest terms, it’s like an engine management warning light to alert you of a problem. Just like your computer pops up with an “error message window” saying that something’s wrong, your service engine soon light pops up to warn you that it has detected a malfunction: mechanical, technical, software, or otherwise.
How to Reset Check Engine Light? This is a great question! I get it all the time. See the guide below.

Source