Coolant temperature gauge not working and no fans - 2.0 tdi bkd

[Beenie]

Evening all,

I’ve tried the search button, google and praying but I can’t seem to get an answer for what the “F” is up with the temp gauge on my a3.

So it’s a 2005 a3 2.0 tdi bkd engine.

I have no temp gauge, the engine gets hot, I have heat coming through the vents but no reading on the gauge. Occasionally if I turn the ignition on and off it might jump up to a different position but it won’t return to the stop.

I’ve replaced both temp sensors, that one at the front is a massive pain in the back side to do. I’m going to replace the thermostat tomorrow as I don’t think that’s working but I can’t figure out why the gauge wouldn’t work.

Also I have the fault code 17075 fan 1 ground control circuit: short to gnd
So I don’t know if it’s getting hot and if it is I don’t have the fans to cool it.

Can someone please point me in the right direction?

 

[Daveyonthemove]

Have you checked your thermostat?

 

[Beenie]

I’ve not checked it, but I will replace it this evening. I’ll update this with the results

 

[Daveyonthemove]

Hope it sorts your problem. The last thing you need in this weather is a car that overheats.

 

[Rideen]

Don't let the engine overheat while you're trying to fix the issue. These have horribly weak cylinder heads which crack easily when engine is overheating. Yours being a 2005, I'd assume is a B revision which isn't as bad as A revision, but still, pay very close attention.

Back on-topic, these might help:

http://wiki.ross-tech.com/wiki/index.php/18068/P1660/005728

https://www.audi-sport.net/xf/threads/17075-fan-1-control-circuit-short-to-gnd.67341/

 

[Beenie]

Lunch time update:

The top radiator hose gets hot, bottom hose is warm, so definitely needs a new thermostat. I have one so I’ll update this again later.

 

[Beenie]

Don't let the engine overheat while you're trying to fix the issue. These have horribly weak cylinder heads which crack easily when engine is overheating. Yours being a 2005, I'd assume is a B revision which isn't as bad as A revision, but still, pay very close attention.

Back on-topic, these might help:

http://wiki.ross-tech.com/wiki/index.php/18068/P1660/005728

https://www.audi-sport.net/xf/threads/17075-fan-1-control-circuit-short-to-gnd.67341/

Thanks for posting this, unfortunately it did overheat yesterday, it popped the temp sensor out of the right hand side and dumped the coolant, I pulled over and let it cool down and topped it back up, it appears to be fine but I won’t know until the thermostat is replaced.

I did read on another thread that if the 2 temp sensors don’t agree on the temperature that can cause the gauge to not function. I don’t know how true this is but it does make some sense.

As I’ve said I’ve googled and searched for this and found no definitive answer, hopefully I can get the bottom of this so no one has to have this problem.

 

[ahtcap]

Is the water pump circulating the coolant?

 

[ch1z64]

Also I have the fault code 17075 fan 1 ground control circuit: short to gnd
So I don’t know if it’s getting hot and if it is Idon’t have the fans to cool it.

Best get that looked at as this will not help your overheating . I had silmar problem with my S3 doing the same and when checked with vcd's live info it was found #1 fan ( big one ) was not working so car was well overheating 109°c changed fan out and all was normal again .

 

[Beenie]

Is the water pump circulating the coolant?

I believe so, the small return at the top of the header tank is push water back into the tank

 

[Beenie]

Update:

If it’s not one thing, it’s another.
So I replace the thermostat tonight, my god is that a horrible job to do. Started it up and bled the system, no movement on the temp gauge. I then turned car off, convinced it was hot enough to show some sort of reading and the needle pops up to about 75 degrees, I turn the ignition back on, another jump to 90 degrees, this continues till I get all the way the end of the gauge.
So I remove the cluster and it’s still sat at 130 even when it’s not plugged in!!
I then went for a drive and the boost hose that’s connected to the egr valve pops off, I pulled over and pushed it back on, guess I hadn’t clipped it back in properly, started the car and drove away, I look down and the gauge is working!! I think, I don’t trust it. But I got home and turned it off and the needle dropped like it should I then turned it on and off again to make sure it was working and it looks like that’s fixed it. I’ll have to wait and see.

Anyway during the whole bleeding process I have the battery warning light on, the alternator isn’t charging. I’m pretty sure I didn’t touch the alternator. There’s no reason for it to have been affected. I’m unsure whether to replace it or try and find out why it’s died all of a sudden.

Onto the fans, I’ve attached a picture of the issue, one of the signal wires was so badly corroded it had split, I tried bypassing the wire with no joy. So I’ve ordered new fans off eBay. But it’s replaced my 17075 fault code with a 18080 fault code. I have no idea whether that’s effecting the alternator issue.

 

[Rideen]

As for 18080, check the 10A fuse next to 474 relay. Might be blown.

 

[Beenie]

Update:

Still no temperature gauge! I’m beginning to think it’s the cluster now.

The alternator fuse had popped, I can only think I’ve shorted it out while replacing the thermostat. New £5 fuse from VW and the alternator is charging again.

The new fans should be turning up tomorrow so hopefully that will be that fault sorted.

 

[Beenie]

UPDATE!!!!

Fix it! So it was the cluster. I bought another second hand cluster off eBay for £19 and swapped the front circuit board with my cluster and everything works as it should.

So the lesson learned is it’s not always the coolant temp sensors!