Coolant temp sensor problem?

[holder]

'98 328IS is giving a check engine light. once briefly before and now constantly after a thermostat replacement and full flush. Advance Auto codes indicate bad coolant temp sensor, thus O2 sensors not enabled. Does the ECU go to a cold start default and stay there? And, if the coolant temp sensor is bad, would it not affect the dash temp gauge , which is fine? Also, if this is it, how to replace it?

 

[fritchy]

A strange thing also happened to me. I got a raditor flush and got BMW coolant added to my car. I believe I had ordinary fluid in it prior. Right after my flush I noticed my car took longer to warm up and it rarely ever reaches the middle. It usually stays around the first mark. Also, my check engine light came on about 5-7 days later. It stayed on for about 3 days and went away for about 2 weeks. It recently came back on for around 2 days and now it is off again. I too am thinking my thermostat and/or O2 sensor. I need to get my error code reading.

You say your temp is fine. Does your car take longer to warm up? Does it not run cooler at all?

 

[holder]

No, car heats up faster, since the t'stat stays closed (not allowing coolant to run thru the entire system, just 'round the block and heater core). Your coolant temp sensor may be picking up your low temp signature, I just don't know enough about them, its my first bmw.
I guess I'm going to throw this CT sensor on and see if that does it. Always strange how one repair cauases another in this car.