Hi all, 2013 Estate 2.0d (168hp) DSG, 138k on the clock, has it since new.

 

For the last few months my temp gauge has been very erratic, not going from cold to 90 in one go, often going up and down, even hovering at about 75, regardless of whether or not the car is travelling fast or slowly. 
 

I had a leaky radiator so didn’t notice originally, had that replaced and thought that would solve it, but no luck.
 

My local (not specialist) garage (no error codes btw) then suggested replacing the water pump (and cam belt (?) which was fine as she is coming up to her 10 year service), which didn’t solve it.

 

We then replaced the thermostat. Still not solved.

 

Any ideas? Like I said, not getting any error codes.

 

Would love to get this fixed as have had the car since new and want to keep it till the wheels fall off, have never had a better all round useful and comfortable vehicle.
 

TIA 

Edited 7 April, 20233 yr by beak

Ah, the suggested posts that come up are very handy, just seen this. 
 

 

Plus one for the DSG stat. Cheap to buy and very easy to replace yourself. Loads of write ups on the forum including mine 

If the gauge is behaving erratically it's probably the coolant temperature sensor. Bad thermostat is going to result in the engine staying cooler than it should be but the gauge will still be stable.

Modern VAG temperature gauges display rubbish, they are programmed to read 90 at 77 and still read 90 at 117, it was to stop people obsessing over the minutiae of the readings so if it is erratic, probably the sensor. I was working on a 2017 S3 yesterday which came in for DSG issues (OTT remap killing the box) and noticed the fan would not shut up, I looked at the gauge and was surprised to see it didn’t have one (never noticed that before) so I looked on VCDS and it was running at 109 constantly at idle, failed thermostat but no indication… daft!

1 hour ago, gav_is_con said:

Plus one for the DSG stat. Cheap to buy and very easy to replace yourself. Loads of write ups on the forum including mine 

Thanks gav will see if I can find yours!