Rory

As I was driving this morning, I noticed the coolant temperature gauge behaving strangely. I'd been driving the car about 5-10 mins and the needle was almost at its center "warm" position, when in the course of 15 seconds it fell back down to cold.

I parked the car to run an errand, and when I came back about 40mins later it was reading warm again, but fell back to cold after a couple of minutes driving.

There are no warning lights on the console, I can blow hot air in the cabin, the coolant level is normal, and the oil temperature is normal (and so is its gauge). Given how quickly the gauge fell, I'm guessing it's a sensor/gauge problem rather than something mechanical. Any ideas?

Thanks
Rory

JasonS4+Festicle

to see if there is a code. There may not be.

I'd change that first. For $6 and 5 minutes it's worth starting there.

You can order one from ECS.

Could be a thermostat also - seems less likely with the number of coolant temp sensors I've seen fail here and the lack of thermostat failures.

Do a search on how to change, there is a write-up somewhere on here.

(Basically, if you remove the accordian hose and looses the ends of the Y-pipe clamps and lift the Y-pipe, you'll have easy access to the coolant temp sensor, it's a little green thing. Make sure the car is cold or coolant will spill out everywhere. When you pull it, make SURE the O-ring comes with it. When you go to seat the new one, make sure the O-ring seats properly or you'll have a leak. Plug the wiring up to the new sensor and you're done.)

Rory

significant for the monkey behind the steering wheel? Just wondering whether the car's performance is going to be impacted in any way (assuming this sensor is the culprit).

Thanks
Rory

Rican_S4

trouble starting the car at times. Like JasonS4 said, it's a cheap and quick fix.

V6UnderPressure

<center><img src="http://pictureposter.audiworld.com/28345/ect.jpg"></center><p>

BTS4

AFAIK there are two distinct readings sent - one is read by the ECU the other goes to the gauge.

Rory

reading the replies here and doing further research myself, there seem to be a number of different names for (possibly) the same part. I have:

* Coolant temperature sensor <a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi/?html=learnmore.html&productID=1484">ECS Tuning's web site</a>

* Coolant temperature sender (Bentley S4 B5 manual, ref: 19-14, part 9, G62)

* Thermo switch <a href="https://forums.audiworld.com/s4/msgs/1629709.phtml">Installation writeup from which SpooledupS4's photo comes from</a>

Are these all one and the same part? Do I need to remove the plastic coolant expansion tank to access the sensor? The "thermo switch" write-up suggests that in tiptronics the sensor may be harder to access: true/false?

Rory

BTS4

Without a manual, I believe A &amp; B are the same; C is definitely a separate item from A.

unash

temp gauge seems dead as well. its impossable to get behind into the temp sensor without moving the coolant tank. does anyone know if you have to drain the tank first or can i just unscrew it and mive it out the way for a while?

unash

yeo some news!!!!

the temp sensor is not behind the coolant tank!!!

if u look behind the engine on the wall, there is another green thing there. thats the one you want to play with!!!