I drive a '84 Oldsmobile Cutlass Ciera with about 90,000 miles. The Check Engine light has been on for quite awhile, but the car still runs OK. How do I reset the Check Engine Light?
By disconnecting the battery for about fifteen seconds, you will clear the trouble codes which are stored in the computer's memory, but you're not exactly resetting the Check Engine Light, and this really won't fix the problem.
If there is a constant fault in the system that set the trouble code, and turned on the Check Engine Light in the first place -- it's still there. The light will be back on in a short period of time. You need a qualified technician to read the trouble codes, diagnose and correct the problem, and then clear the trouble codes in order to keep the Check Engine light out for good.