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Discussion Starter #1 (Edited)
My ambient temp/sensor reading isn’t working (-40). Actual ambient temp during photo was 54F.
Tstat and coolant temp sensor replaced 10k miles ago. Sometimes my gauge reads even lower when cruising as 2nd pic shows, notice how engine oil temp is optimum and I’m at 3k rmp in 3rd probably doing about 60mph
05B6CD24-561D-4063-BC1C-AB569D12692A.jpeg
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On the ambient, you have an open circuit. If the sensor is still there, one of the wires is likely broken.
 

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My main concern is the coolant gauge reading right now.
What tstat did you install? It is common for the tstat to fail prematurely.

Also which temp sensor did you replace? There are 2 different sensor for the coolant:

13621703993 - on the tstat housing
13621433077 - on the coolant return hose
 

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Discussion Starter #5
I replaced the one on the housing. You really think the Tstat failed already? I replaced it 10k miles ago and I’m getting an 81C readout in the hidden menu. I think the gauge is off a bit.
 

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I replaced the one on the housing. You really think the Tstat failed already? I replaced it 10k miles ago and I’m getting an 81C readout in the hidden menu. I think the gauge is off a bit.

I've had behr units fail at about the 1 yr mark, mileage was probably a little more than yours. The Stant 82F thermostat failed after only a few weeks.

The gauge is likely reading a bit off due to the new sensor; I had my oil temp gauge do that after replacing the oil level/temp sensor in the oil pan. If it bothers you you'll have to find a way to recalibrate the positions. I haven't done this, but a secret menu test #2 &/or #21 might reset it, that's just a guess though.

To test the thermostat you need a decently cold ambient temperature to get an accurate result. There are two methods of checking, you can try them just in case.

Test must be performed on the highway where you can keep a steady speed for many miles.

Method 1
-Get onto the open highway BEFORE the coolant gets too close to the 70C range
-Drive in 6th gear, no need to speed (2000-2500rpm should be perfect)
-Maintain steady speed & rpm
-Observe temps climbing towards 79C
Failed thermostat will not reach 79C, instead it will dip back down somewhere before 79C.
(e.g. it reaches 78C, and then dips to 77C instead of going up to 79C)

Method 2
-While on the open highway AFTER the coolant temp is well passed the 79C/80C mark
-Drive in 6th gear, drop you rpms down into the 2000-2500rpm range
-Maintain steady speed & rpm
-Observe temps drop towards 79C
Failed thermostat will allow coolant temperature to dip below 79C
 

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Discussion Starter #7
I did the t stat test no drops at all my gauge is just off a few I’ll probably just deal with it.
 

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Discussion Starter #9
My coolant gauge is off, My ktemp will remain at 80C or above but my temperature gauge only goes to about a quarter. Is there a way I can recalibrate the Temp needle?
 

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Do you know what test # in the secret menu recalibrates?
Try Test #2 with the car off to check the whole cluster. If the Radar guided cruise control light stays on afterward it's likely your cluster was replaced by BMW at some point. Test #21 will shut off the radar guided cruise control light, among other resets (which I can't verify).
 

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Discussion Starter #11
I figured it out my temp gauge needle rests too low below the first white line on the gauge. I just had my cluster rebuilt so they probably moved it off a bit
 
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