Recently had the exact same issue on a 14 a6 ended up being a DOA t stat I compared the shaft length on the new t start to the 2nd new t stay and sure enough it protruded out about a mm further just enough to not seal properly causing the over cooling after the swap no more issues.
I have an 06 Audi A3 2.0T Sportback with just over 105k miles; recently replaced the thermostat, spark plugs and coil packs. Other than being in need of some new brakes and a bit of cosmetic love, she's running strong.
Had this happen to our 2018 Q5 a few months back, 35k miles on the SUV. Thermostat issue plus some other stuff.
My Q5 with 75,000 miles on it developed a leak in the water pump area. Initially Audi denied there was a leak, so I took pictures and showed it to them. Then they diagnosed it with thermostat leak.
Not the water pump but I just had my thermostat replaced under the extended warranty. I was slowly losing coolant with no discernable leak.
I just got this done and Audi quoted me $2500 for just the thermostat. Mine was covered by the extended warranty Audi has on all water pumps leaks.
the 80c has been running flawless. Only difference is that my coolant stays at 83-94c. It used to get as high as 100 sometimes. Also the 80c part was recommended oe part #
Been running the 80 for a month or so. It works great. Car and Temps run flawlessly. Only difference is my average warmed up Temps are 85c. Used to be 95c
The current plastic thermostat looks a little more beefy, but is still shatty plastic. They're commonly failing at 30-55k miles in the stuck closed position, instant overheat.
I finally got around to installing a new thermostat/o-ring/housing and coolant reservoir/cap yesterday. When removing the thermostat, I noticed that the bottom bolt was VERY loose... I had done the thermostat without housing about a year ago now, had never leaked coolant before... My best guess is that I just didn't torque it enough and it slowly loosened, but only when cold (just a guess, but would help explain why no drips when car was running on ramps) and in small enough amounts that I did not notice a puddle on the ground.
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What we know about OEM Audi thermostat
The brand is registered in Germany.
In March 2026, PartReview users have a positive opinion of OEM Audi thermostat.
PR Score — 75 out of 100, based on 11 reviews and 36 votes. 7 positive reviews, 3 neutral reviews, 1 negative review. Average rating — 4 (out of 5). Vote balance: 27 up, 9 down.
In the ranking of the best thermostat this part is at position 7, behind OEM Honda and AISIN , but ahead of Motorcraft and OEM BMW.
Users also evaluated the qualities of OEM Audi thermostat:
- Slow warm-up - engine takes a long time to reach normal temperature - no rating yet
- Overheating - temperature gauge rises quickly or fluctuates - rated positively. 4.1 points out of 5.
- Cabin heat - heater blows weakly or becomes too hot at the wrong time - no rating yet
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Thermostat OEM Audi in comparisons
There are 14 comparisons of OEM Audi thermostat with other manufacturers on PartReview.
In particular, see which thermostat are better: OEM Audi or Motorcraft, OEM Audi or Duralast, OEM Audi or AISIN, OEM Audi or MotoRad, OEM Audi or OEM Nissan .