Here's the proper approach:
1. Diagnose the Problem: The CEL is a symptom, not the problem itself. You need to find out *why* the light is on. The most reliable way to do this is:
* Obtain Diagnostic Codes: Use an OBD-II scanner (available at most auto parts stores for around $20-$50). Plug it into the OBD-II port (usually located under the dashboard) and it will read the diagnostic trouble codes (DTCs). These codes will give you a clue about what's wrong. You can then look up the codes online (many free resources are available) to get a description of the problem.
2. Repair the Problem: Once you know the DTCs, you can either attempt to repair the problem yourself (if you have the mechanical skills and tools) or take your Monte Carlo to a mechanic. Fixing the root cause is crucial.
3. Clear the Codes (After Repair): *Only after you've repaired the problem* should you clear the codes. Many OBD-II scanners have a "clear codes" function. Some auto parts stores will clear them for free if you bought the scanner there. After clearing the codes, drive the car for a while to allow the system to monitor for any further issues. If the light comes back on, the problem hasn't been fully resolved.
Do NOT simply disconnect the battery to reset the light. While this might temporarily clear the light, it won't fix the underlying problem and could erase important diagnostic information needed for proper repair.
In short: Fix the problem, then clear the codes. Attempting to reset the light without fixing the problem is a dangerous shortcut.
