Here's what you should do:
1. Get the Diagnostic Trouble Code (DTC): This is crucial. You need to know *why* the light is on. You can do this in a few ways:
* OBDII Scanner: This is the best method. Buy a cheap OBDII scanner from an auto parts store or online. Plug it into the OBDII port (usually under the dashboard) and it will read the trouble codes. These codes will tell you what system is malfunctioning (e.g., oxygen sensor, mass airflow sensor, etc.).
* Auto Parts Store: Many auto parts stores will read the codes for free. Just bring your car in.
2. Address the Problem: Once you know the DTC, you can research the problem online or consult a repair manual. Sometimes, it's a simple fix (like a loose gas cap), while other times it requires more extensive repairs. Attempting repairs yourself depends on your mechanical aptitude.
3. After Repair: Once you've repaired the issue that caused the CEL, drive the car for a few days or drive cycles (this varies depending on the car and the problem). The computer monitors the system, and if the problem is resolved, the light will usually turn off automatically after a certain number of successful drive cycles.
Don't attempt to reset the light without fixing the problem. Some people try to disconnect the battery, but this is only a temporary measure. The light will likely come back on if the underlying issue persists. You'll be masking a potential problem that could lead to more expensive repairs down the road. A properly functioning car needs all systems operating correctly.
In short: Find the code, fix the problem, then the light will go out.
