Temp gauge

[dreddfan]

My temp gauge on the dash has stopped working recently.
Does anyone know where i should start looking for a probable cause? I've seen online that the coolant temp sensor in the B5 can be weak and prone to failure. Where is this sensor mounted in the engine?

Any help would be welcome.

MS.

[avant adam]

I thought I had this problem too. Turned out I was just a little low on water and the outside temp is cooler too so it's not getting that hot. Sits below 70 degrees all the time now


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[Doctle Odd]

70 degrees is far too low for the car to run efficiently. I usually have a spare coolant temperature sensor, they are known to fail and a genuine VAG one isn't very expensive. It's on the pump side of the engine behind the crankcase pipe 4 wires going to it. It can be blue, green or black in colour. It's held on with VERY easily broken clip but if you buy one it won't break. Sods Law! drain a couple of pints of coolant with the engine cold its a 10 minute job

[Randomhedgehog]

If the gauge is still moving a bit but not showing as up to temperature on a run, such as it only reaching 70, it may be the thermostat is stuck open. If you set the climate control to diagnostic mode on channel 49 you can read the coolant temperature direct from the sensor which may help narrow down the problem.

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[dreddfan]

Thanks for the info.
I'll ring the local dealer and get a price on the sensor. Anyone have a part number for it?
I've also noticed my electric heated wing mirrors are always on as well, could this be related??

[Doctle Odd]

No part no off hand but engine code will get you the correct sensor

[dreddfan]

I finally got around to getting the sensor and installing it but i still have the same problem.
I'm now looking at replacing the thermostat but I have like to find a how to guide for this job.
Anyone know where I'd get one?

[HAWKS]

What Audi is it... ive just rang Preston Audi for a quote to replace my thermostat on A4 2.5tdi Q. £708 + VAT This includes cambelt kit+stat(28+vat)
I am in the process of having a remote stat housing made. I will keep everyone posted on here.

[dreddfan]

Its a 99 A4 B5 1.9 tdi.
Still looking for a good 'how to' for this job if anyone knows where I'd get such a thing.

[jas828]

done mine other day mines fitted with afn 1.9tdi engine and it was down below alternator exiting engine behing angled plastic water stub needin 5mm allen key to remove 2 bolts and then remove plastic stub and there will be o ring and then thermostat dont forget to drain coolant first and if you not reusing coolant you will g12 do not use blue or green as they will react with existing coolant

[Doctle Odd]

Drain coolant there should be a drainage tap on the bottom of the radiator
Jack up the car and put it on axle stands or drive it up on ramps
Remove undertray if its there
There's a bar coming from the front snub mount bracket to the engine mount remove this for access if you cant see clearly
Remove the 2 x 5mm hex bolts from the black plastic thermostat housing and put a bucket under it
From the top reach down and wiggle the thermostat housing free. Doing it from the top you won't get a face full of coolant
Go under the car again remove the old thermostat and seal.
Clean everything with rags
Fit new thermostat and seal
Put it back together and add NEW coolant
Check for leaks
Job done

Its a 99 A4 B5 1.9 tdi.
Still looking for a good 'how to' for this job if anyone knows where I'd get such a thing.

[dreddfan]

managed to find a spot to run the car up on where I could get under and have a look. It looks simple enough so I'll have a go Thursday evening.

[dreddfan]

Got the coolant flushed and thermostat in ok but the resulting airlock was a b***h to clear. Finally got rid of it and now my car is actually warm on the inside.
The Temp gauge is back working again, siting dead at 90 thank god.
The Thermostat was a bit of a fecker to get into place but I got it in the end.

One thing I would add to Doctle Odds post is that after filling the coolant tank and topping it up a few times, I had to park the car facing up a hill, get a mate to rev it and then pull the bleed pipe down to get more of the air out. Even when I thought it was all gone, there was more so keep bleding till it hits the underside of the bonnet :)

Thanks for all the info and help. wouldnt have been as easy without it.

[Doctle Odd]

Your 2nd thermostat will be a tea break job! You can bleed it yourself after a quick 5 mile spin with the engine ticking over

[dreddfan]

Hopefully I wont have to do it again for quite a while ;)

[audia4lyn]

Have a look here:
AudiWorld Tech Articles (http://www.audiworld.com/tech/eng54.shtml)