What would cause the check engine light to come on with a 92 16v, 5 speed, I cleaned the air filter with no change, it will come on at idle shortly after startup and go off when I cycle the switch, then come back on.

 

Are we talking a gasser here?

Either way, there's no need to guess about it. Pull the trouble codes, there's a link in the sticky thread at the top of the forum that will tell you how. No tools needed.