My "check engine" light used to come on once in a while. I read the code and it indicated the exhaust gas analyzer in the catalytic converter. It used to come on when the engine reached operating temperature. The engine would also hesitate for an instant, then resume operating as normal. After a few stops and starts within an hour or so, the engine light would go out. This happened just about every time I operated the car for a few months, then stopped. I don't have that problem anymore. The car runs OK.