[Judge Dredd]

On the way to a BMW CCA meet, my '06 330i threw a P0128 code (coolant temperature below regulating temperature). Reading online tells me the thermostat is probably stuck open. I plan to get it replaced but until then, I'd like to clear the code and turn the light off. I plugged my code reader into the OBDII port and tried clearing it a few times, both engine on and off, but the light wont clear. How can I clear it?

[Nanometer]

I'm no engineer, but I would guess replacing the thermostat or coolant level sensor would fix it.

[Judge Dredd]

Originally Posted by Nanometer

I'm no engineer, but I would guess replacing the thermostat or coolant level sensor would fix it.

Do you know how to read?

[Meeni]

Do you? Error will return until triggering condition is fixed.

[Judge Dredd]

Originally Posted by Meeni

Do you? Error will return until triggering condition is fixed.

Yeah, I do. In case you didn't know, you're supposed to be able to clear these codes, regardless of whether they will come back. My problem is that I cannot clear the code and am looking for a solution.

[Three_thirty_I]

Judge Dredd, I am really curious to know what sort of running temperatures your car shows in the hidden menu! Mine sits between 79 and 84 degrees Celsius (supposed to normally sit at 105 or a bit below depending on the type of driving). Now the annoying thing is I don't have any error codes, but earlier this year replaced both temperature sensors thinking that there was an issue with them, no such luck. So will have to just replace the thermostat and see if the engine then runs at the correct temperatures.

[Judge Dredd]

Originally Posted by Three_thirty_I

Judge Dredd, I am really curious to know what sort of running temperatures your car shows in the hidden menu! Mine sits between 79 and 84 degrees Celsius (supposed to normally sit at 105 or a bit below depending on the type of driving). Now the annoying thing is I don't have any error codes, but earlier this year replaced both temperature sensors thinking that there was an issue with them, no such luck. So will have to just replace the thermostat and see if the engine then runs at the correct temperatures.

I'm curious too! I am going out to dinner tonight and if I remember, I will try to get a reading for you.

[Three_thirty_I]

Originally Posted by Judge Dredd

I'm curious too! I am going out to dinner tonight and if I remember, I will try to get a reading for you.

Cool, look forward to your post! Enjoy dinner!

[Judge Dredd]

Originally Posted by Three_thirty_I

Cool, look forward to your post! Enjoy dinner!

Just went out to my car to see if I could get a reading early. Purely by accident I noticed the light has now gone off so I am assuming the issue is gone for now (I didn't clear it). I suppose I could still get a reading for you if you want. Just let me know.

[Efthreeoh]

Probably what is happening is the heater in the thermostat is bad, which will throw P0128. You can clear it with a scan tool, so maybe you are not using the scan tool correctly (not intended to flame). If the heater is bad in the t0stat, it will continually throw the code.

Replace the t-stat and you'll be good to go.

[Three_thirty_I]

Originally Posted by Judge Dredd

Just went out to my car to see if I could get a reading early. Purely by accident I noticed the light has now gone off so I am assuming the issue is gone for now (I didn't clear it). I suppose I could still get a reading for you if you want. Just let me know.

Glad to error is gone now! I would still be interested to see what sort of temperatures you see, and how it fluctuates etc. Mine tends to briefly climb to say 96 degrees Celcius at times, but the moment I slow down or stop it falls down quickly to the low 80's! Most of the time it seems to sit between 79 and 84 degrees Celsius though (174 - 183 F). Also the fan comes on very quickly even when the car is just about getting up to temperature, so definitely over-cooling. But no errors of the cluster or error codes when connected to diagnostics.

So from interest sake I would really appreciate this!