How do you reset the service engine lights on a 1998 buick century?

The 1998 Buick Century doesn't have a simple button or procedure to reset the Check Engine Light (CEL) like some newer cars. The light comes on because the car's onboard computer (PCM) has detected a problem. You must fix the problem that triggered the light, then the light may reset automatically after several driving cycles (start the car, drive for a while, turn it off).

Simply disconnecting the battery or using a code reader to clear the code *without fixing the underlying issue* will only temporarily turn off the light. The problem will likely reappear, and ignoring it can lead to more serious damage.

Here's what you should do:

1. Get the diagnostic trouble code (DTC): The best way to know what triggered the CEL is to have a mechanic or auto parts store use a code reader to retrieve the diagnostic trouble code(s). This code will tell you specifically what the problem is. Many auto parts stores offer this service for free.

2. Repair the problem: Once you know the code, you can research the problem and either attempt the repair yourself (if you're mechanically inclined) or take it to a mechanic to get it fixed.

3. Drive the car: After the repair, drive the car for several drive cycles (start, drive for 15-20 minutes, turn off). The computer will monitor the system, and if the problem is resolved, the Check Engine Light (CEL) should turn off automatically.

4. If the light remains on: If the light stays on after several drive cycles, there might still be a problem, the repair was incorrect, or there's a more complex issue. Return to step 1 and have the code rechecked. A professional mechanic may be necessary at this point.

In short: There's no reset button. Fix the problem, and the light should go out on its own. Ignoring the light is strongly discouraged.