I have been trying to get my 97 Sunfire to pass a smog check for several months. It continues to fail because the check engine light is on. The codes reported are PO121 (TPS performance), PO141 (Heated O2 Sensor circuit error) and PO 336 (Crankshaft position sensor malfunction). The first garage I took it to wanted to replace all 3 sensors for $400. I took it to another guy who seemed certain that the problem was related to a grounding issue. In addition the engine runs fairly hot while idling, and randomly fails to start.

Anybody have similar experience or suggestions?

well I would probably get those sensors replaced, the o2 sensor is the 2nd one in line and checks how your cat converter is doing, and if your tps and crankshaft position sensor is out it is amazing that the car starts at all, since the computer uses both of those to get the car going, so right now the car is running in a fail safe mode, till you get those sensors replaced. I doubt it is a grounding problem since all of those sensors use different grounds.


This is my 5 cents worth, (normally is would be 2 cents worth but I have adjusted it for inflation)

Car I drive:
99 Chevy Cavalier 2.2L 5 spd man (My daily car)
98 Ford Escort ZX2 4 spd auto