With a code reader you might find you can simply turn off the check engine light yourself. However, if you haven’t fixed the problem, it will eventually come on again.

Remember, the code reader won't tell you how to fix the check engine light—the code it reads just directs you to the fault. From there, unleash your mechanical prowess and discover the cause!

Consumer Reports explains what the check engine light means and what to do when you see it: how to tell if your car has a loose gas cap—or a serious engine problem.

Discover what an OBD2 scanner is and how to use it to diagnose and fix car problems before they escalate into major repairs.

Do 'check engine' codes mean Camry needs new catalytic converter? Q: I have a 2003 Toyota Camry with the "check engine" light on. A code reader shows codes PO430 and PO420. How should I proceed?