fluctuating water temperature gauge....

Post by **rhunter203** » Wed Nov 19, 2008 3:41 pm

The water temperature needle rising between 75 and 90. The needle normally sits in the middle on 90. Any ideas??? Maybe the thermostat is knackered??
Cheers
Rob

Post by **Sql_RS4** » Wed Nov 19, 2008 4:37 pm

Happened to me too.

You need to change water temp sensor.

Post by **boxerdogted** » Wed Nov 19, 2008 8:47 pm

Try the sensor first, mine was the thermostat in the end.

Post by **S4INT** » Wed Nov 19, 2008 10:56 pm

Yep - thermostat I'm afraid. Big job as the cambelt/water pump etc has to come off.

Try the sensor first as its cheap and easy to do, but I have had these symptoms on both my B5's and both times it was changing the thermostat that cured it.

Post by **rhunter203** » Thu Nov 20, 2008 12:32 pm

Cheers guys!!!

Post by **polly_x** » Sun Nov 23, 2008 1:06 pm

Does the green temp sensor feed just the gauge on the dash or does it also give the engine management its water temp too? (or is there another separate sensor for the ECU)

Stu

Post by **Virdee Autos** » Sun Nov 23, 2008 4:25 pm

Yep the green 4 pin sensor does work with the engine management aswell.

Post by **polly_x** » Mon Nov 24, 2008 3:31 pm

Virdee Autos wrote:Yep the green 4 pin sensor does work with the engine management aswell.

Cheers.

So if the sender is faulty (vagcom says it is) the dash dont work and I guess the ECU is seeing the wrong signal or that the car is stone cold all the time? It still runs really nice which is odd as I thought it would have at least some effect on the mapping.

Will change it tonight then as ive had a new one on the garage for 2 weeks now!

Any links to guides on how to do it on here? Or is it just a simple remove covers and what else?

Ta

Post by **s4-99** » Mon Nov 24, 2008 4:19 pm

Have a read of this...This is for an S4 but i presume it's the same for the RS4

http://www.rs246.com/index.php?name=PNp ... torder=asc

3rd post down tells you how to change it...

Post by **SimonC** » Mon Nov 24, 2008 4:20 pm

Had mine done under warranty last year (went to open circuit during warm-up. Vag-com is brill!) Only advice I can offer is that the technician bled on my engine so beware of sharp edges.

Post by **Virdee Autos** » Mon Nov 24, 2008 8:06 pm

Yes this also controls the temp gauge in the instrument cluster

After you've changed it you'll notice the car is more responsive

Post by **Blue_Thunder** » Mon Nov 24, 2008 9:31 pm

I believe two pins send a signal to the cluster and the other tow pins send a signal to the ECU.

When my temp gauge started playing up it would just drop off the scale. Using the Climate Control to check the temp being sent to the ECU showed that it was still sending 90 to the ECU. Turned out to be a split wire on the sensor, but replaced it anyway with it only costing about a tenner.

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fluctuating water temperature gauge....

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