If you didn't retrieve the code from the system yet, you have to do that first. If you can't retrieve a code, or you are getting erratic or un-resettable behavior, the problem probably resides elsewhere.

The most common is a "5" which is bad airbag module, I believe. It's often seen after the battery runs down, there is some sort of power fault, or a jumpstart, among other reasons. That particular code often doesn't reappear after resetting it.
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1992 940 wagon, 72k
make people envious; smile often.