Instead of resetting it, you should:
1. Get the diagnostic trouble code (DTC): This is the key to understanding why the light is on. You have a few options:
* OBDII scanner: The cheapest and easiest way is to buy a relatively inexpensive OBDII code reader at an auto parts store. Plug it into the OBDII port (usually under the dashboard) and it will tell you the trouble code(s).
* Auto parts store: Most auto parts stores will read the codes for free. They can then help you determine the likely cause.
* Mechanic: A mechanic will have the most sophisticated diagnostic tools and expertise.
2. Address the problem: Once you know the DTC, you can research it online (many resources are available) or consult a mechanic to determine the cause and repair it. Common causes include a faulty oxygen sensor, mass airflow sensor, or something as simple as a loose gas cap.
3. After repair: *Once the problem is fixed*, the check engine light will usually turn off after a few driving cycles (the car's computer monitors the system for a while to ensure the problem is resolved). If the light stays on after driving for a while, there might still be a problem.
Do NOT attempt to reset the light by disconnecting the battery. While this might temporarily turn off the light, it won't fix the underlying issue and could erase valuable diagnostic information. It's a band-aid solution that will likely result in the light coming back on.
In short: Focus on *fixing the problem*, not just the light. Getting a diagnostic code is the first crucial step.
