Any idea why my car is running on limp mode? My car is running on a p28 and it runs fine before I took the ECU out last night. I plugged the ecu in this morning and the check engine light is on. The engine idles at 1500rpm at normal driving temperature. Is it possible that I have a bad ecu? I haven't had time to check any cel codes since I'm still at work. Any thoughts or input on this?

 

what makes you think that you are in limp mode? your idle will be off at first until the ecu re-learns the engine. If you have cels, get the codes before you start worrying about a bad ecu.