I have a 1999 Sunfire with the 2.2L OHV engine. The cooling fan would start soon after the engine was running. I installed a new coolant temperature sensor, but the fan still starts before the temperature gauge needle even moves. Now I'm thinking either the PCM or the temperature gauge is faulty. Anyone have any ideas?

My thoughts would be to first check:
1. Is the A/C being commanded "on" by either the car being in defrost mode or the A/C turned on (if equipped)? The fan will always run when the car is stationary if the A/C is trying to operate.
2. Is there a misfire code set (PO300 to P0304)? Any of these will cause the fan to run once set. It's probably to keep air moving around the converter and exhaust, since it may be getting overloaded with unburnt fuel. Other codes may also cause this, but I'm familiar with this from personal experience.

Thanks John,
1. I forgot to indicate that the car does not have A/C, so that eliminates one possibility.
2) It did have a misfire code due to a failed head gasket, but I thought I had deleted the code. Maybe it is still there and worth checking out.
Again thanks, Paul.

since someone mentioned ac here, that brings to mind a question you said as long as the car is stationary like sitting at a red light etc the fan will run does the fan continue to run after you hit road speed or is it just the compressor running at that point and the second you stop again the fan kicks back on. Also is there a way to adjust when the fan comes on and does not come on or can only the computer do that.