CEL code P0128, bad thermostat?
 

My CEL came on today, had the code read at a local parts store, P0128.


I can only imagine that this means my thermostat has failed in the open position and needs to be replaced.

Thoughts?

That, or the integrated Coolant Temperature Sensor (CTS) is faulty.
Either way, you're looking at a thermostat housing replacement.

- Erik

Is that the only coolant temp sensor on the motor?

A few month back, I had a coolant temp sensor replaced by WMW, but there is no CEL for it. The fans were constantly running hard, and it was determined that the sensor was running high. But, there was never mention of the tstat and housing being replaced as well.

The part cost for the sensor was only $20, the housing and whatnot appears to run around $100 or so.

Yes, it's on the thermostat housing.
However, I misspoke; the thermostat can be purchased separate from the Coolant Temperature Sensor (CTS).

http://www.realoem.com/bmw/diagrams/e/x/320.png

- Erik

Yea, looks like it can be separate. Item #5 was probably what WMW replaced a few months back. Pricing looks similar too.

So either that sensor has failed, or the tstat itself?

Going to the dealer on Monday. Curious to see if its the tstat or temp sensor.

It was indeed the tstat, should have the car back this evening.