That said, there are two ways to clear the code (and thus the light) but only after you've determined and fixed the issue:
1. OBD-II Scanner: This is the recommended method. An OBD-II scanner (available at most auto parts stores for around $20-$50) will allow you to read the diagnostic trouble codes (DTCs) stored in your car's computer. This tells you *why* the check engine light is on. Once you've fixed the problem causing the code, the scanner will allow you to clear the code, turning off the light.
2. Disconnecting the Battery: This is a less reliable method and isn't recommended. Disconnecting the negative (-) terminal of your battery for about 15-30 minutes will often clear the code, but it doesn't guarantee it, especially on newer systems. Also, disconnecting the battery can cause problems with some electronic settings in the car, such as radio presets. Only do this after attempting to find and resolve the issue causing the check engine light.
Important Steps:
1. Diagnose the problem: Don't just try to reset the light. Find out *why* it's on. Use an OBD-II scanner to get the code(s). This code will point you towards the likely cause (e.g., a faulty oxygen sensor, mass airflow sensor, etc.).
2. Repair the problem: Fix whatever is causing the check engine light. This is crucial. Ignoring it can lead to further damage.
3. Clear the code: *After* repairing the problem, use the OBD-II scanner to clear the code. If you used the battery disconnect method, try starting the car, and see if the light goes off. If the light stays on after the repair, there might still be a problem that needs attention.
In short: Fix the problem, then clear the code. Ignoring the check engine light is never a good idea.
