tracking / coolant temp sensor

[redpriest]

Originally Posted by roastbeef

how easy is this to replace? is it DIY in a few minutes? i don't want this to ruin a weekend...

It costs about 3 hours in billed labor, so I doubt it's that simple. Looking at the DIY for thermostat replacement ... it looks so involved that I don't want to do it myself.

[roastbeef]

Originally Posted by redpriest

It costs about 3 hours in billed labor, so I doubt it's that simple. Looking at the DIY for thermostat replacement ... it looks so involved that I don't want to do it myself.

well damn. are you still having temperature issues? i know you have a habit of destroying your front undertray. i wonder if that sensor gets fried and quits. does it mess with the thermostat at all? like keep it open?

[redpriest]

Originally Posted by roastbeef

well damn. are you still having temperature issues? i know you have a habit of destroying your front undertray. i wonder if that sensor gets fried and quits. does it mess with the thermostat at all? like keep it open?

Well my tray is fully intact, I haven't hit any streets of willow sized boulders . I have no idea what's causing it to fry. My oil temperatures are totally fine, which is the weird thing.

I never budged above 245/250 all weekend long. If it's having an impact on performance, it's a subtle one, only looking at the data does it look like I don't have as much power > 90 mph, and who knows, that could be weather. A really consistent 2:00-2:02 lap range 3 weeks ago turned into me struggling to get 2:04-2:06, and only at the end of the day did I manage to claw back to 2:02.

What it does do, is that at idle, the engine does not want to stay at 700 RPM, but will start to bounce, and sometimes stall.

[redpriest]

You can see the exact moment the sensor crapped out on the track - during my 2nd lap of the day here. The orange line in the top left graph is the water temp. Y-Axis is temperature, X-axis is distance traveled from the starting point in feet. Jumps from 185 to 405, a totally bogus figure.

[redpriest]

This is pretty much me:

[roastbeef]

Loooooooooooooool


does your tune take you up to 8,600 rpm? moar rpm = moar heat = moar problem?

[redpriest]

Originally Posted by roastbeef

Loooooooooooooool


does your tune take you up to 8,600 rpm? moar rpm = moar heat = moar problem?

I do but I rarely hit it at the track. It's hard to time it exactly, and you don't want to get fuel cut when you're trying to accelerate! I think I have some gremlin somewhere that is going to cost me hundreds of dollars to fix.

[kenwelch]

Originally Posted by redpriest

Bumping this old thread since I have this issue - replaced it once already, and the damn thing came back again after three weeks! Anyone else have this problem, and how did you resolve it? radiantm3

I did a TSB search to help you.
Found TSB 12 07 12 from April 1 2012. I have attached the PDF file.

You will notice that BMW also has determined that the connector might need replacement and developed a "coolant temperature sensor harness repair kit".

There may be some sensors that are being replaced when the connector is the faulty component. The connector replacement is more difficult to replace than the sensor. Good news for some is the TSB repair is covered under the Emissions Warranty which is beyond the New Vehicle Warranty. See the Warranty Information section of the TSB.

Here are the Coolant Temperature resistance values for those with an Ohm meter. There are YouTube videos on the test procedure for testing the sensor without removal and sensor operation description.

Coolant temperature sensor

Warning: The coolant temperature sensor is destroyed in the case of short circuit to B+.

Nominal values for resistance test:
◦Resistance at 20 °C: 2.5 - -3.0 kOhm
◦Resistance at 50 °C: 0.7-0.9 kOhm
◦Resistance at 100 °C: 0.12 - -0.17 kOhm

This is a negative temperature coefficient (NTC) sensor, the internal resistance will decrease as the temperature rises.

[dbyrd]

Hey Folks,
Did anyone ever get to the bottom of this?

My Aim has been defaulting to 404 degrees and I'm getting the temperature sensor CEL.

Thanks!