How to change/find coolant temp sensor?

**rice_Rocket88** · 10-31-2008 08:29 AM

Just realized the coolant temp sensor wasn't budging..

Seeing as it's cold outside now, and my temp is acting completely fine... I'm certain it's a dead sensor.

I've found a few writeups for A4's.. anything for the A6?

I suppose I could just ignore it for a while, but why have a dead needle? :)

**j_v_z** · 12-15-2013 04:38 PM

bump for this guy, i also need help w/this

**Audi_Tech** · 12-15-2013 04:51 PM

Originally Posted by rice_Rocket88

Just realized the coolant temp sensor (you mean gauge?) wasn't budging..

Seeing as it's cold outside now, and my temp is acting completely fine... I'm certain it's a dead sensor.

If you have access to a scan tool then perform a guage sweep in the cluster via output diagnosis as this will run the gauges from left to right and end dead center. If this is not the case then you have a guage problem since inputs to the gauges are disregarded during this test.
If the temp gauge ends in the center then check the value block for temperature in the cluster (can't remember channel number, check 1-3) and compare to value block 4 field 3 or 4 of the ECM. They should be the same. The coolant temp sensor uses two pins for the ECM and two pins for the cluster.

As far as replacement, release pressure in the system by loosening/fastening the reservoir cap.
Remove the retaining spring clip for the ECT sensor and wiggle sensor back and forth to separate it from the old o-ring.
Remove sensor connector, removed old o-ring, trash old sensor/ring/spring clip. Remove and flaky deposits in coolant pipe housing.
Check sensor/connector housing for coolant leaking through sensor and into housing - coolant can migrate through wiring harness to ECM or cluster.
Install new o-ring on sensor and lube with coolant.
Insert sensor into connector and assembly into coolant pipe housing with slight rocking motion to seat o-ring/sensor.
Secure with new spring clip.
Top off coolant and drive to bleed system.
Re-check coolant level.

**troyguitar** · 12-15-2013 04:57 PM

There is a video on youtube of a guy trying to change it on an allroad. He ultimately fails but the video will show you exactly where the sensor is located at least. Mine was bad when I got my car too, took 15 minutes to swap it out.