Thanks jon, so what youre saying is that even though the check engine light is on there should be no problem? hope that is a fact. My mechanic can find nothing wrong since he replaced the tcu. No codes showing. Ive read that once a check engine light has come on and the repair made, the light stays on for so many miles because the car is running its own diagnostic check and will go out by itself. Please advise if this is correct. thank you much.