Cooling temperature starting to creep up, fan staying on. Sounds like Thermostat?

[David655321]

2011 S4, 51k miles, DSG, not sure if thermostat was ever replaced, never had any luck getting a straight answer from Audi.

Searching the forum, it seems like this is def a thermostat issue, but maybe after posting more details someone will have some insight.

After getting home, noticed the cooling fan stayed on for less than a minute after turning engine off. Using the torque app started watching cooling temps today. Before, it seemed like the cooling temp would be right around 98 C once it is warmed up. A/C still works, but now temp seems to be between 105 and 111 C. The needle is still in the middle, but I know that is a wide range. It hasn't given any warnings as far as temperature, but Torque is showing it is running warmer. The coolant levels seems fine/normal. I noticed pulling in my driveway the fan was running, then it stayed on just briefly after I turned the engine off.

Does the fan ever stay on if there is not a thermostat issue? Or could be something wrong with the fan electronics?

But more likely a thermostat issue?

Thanks in advance.

[Dr GP]

If the fan just ran briefly, you MAY be ok. But I would watch it closely. I will be surprised if the T stat is not on its last legs

[fitzydude]

Keep watching the temps in torque, it's probably on its way out. When it fails further crank the heat up! It helped get me home when it happened to me. The needle will not go past the middle until it hit temps of 120C +

[David655321]

Thank you Dr GP and fitzydude. Good to know that the temp will creep past the middle at about 120C. As far as I can tell the highest it has gotten to is 111C. Will call the Audi place in Marin tomorrow, but I assume they probably won't do anything until it totally fails. I am just trying to be proactive and take care of it sooner than later.

[David655321]

Yep it was the thermostat of course. Luckily I was observing coolant temp via the Torque app and noticed that the fan was running after car was turned off. Drove to dealer very carefully and with the heater full blast. Replaced under warranty, so good to go.

[mitko]

Did you have to wait for it to fail completely before the dealership would look at it, or they were able to diagnose and warranty it just based on the readings from torque and the fans running constantly? I'm in the same boat, I noticed a few days ago that my fans are running at full blast and saw the coolant get up to 114C but still no warnings and the gauge on the dash still hasn't moved from the middle. It's definitely on its way out and hopefully I wont have to wait to get stranded and get it towed to the dealer before they look at it.

[Tanner]

I tried to get the dealer to look at the issue as I knew when I had the t-stat issue, it was on the way out. Left it with them for the day, they just drove around and never saw any issue, I asked if they noticed if the radiator fan came on, they heard it but didn't think much about it. Argued with them that the t-stat was on the way out and wanted to address it before I end up being stranded somewhere. They refused. What happens three days later? The thing finally gives up, manage to get home. And instead of using my CAA to tow the car, I used Audi Roadside Assistance. Told the service manager that this was a waste of everybody's time which all could have been avoided if they just addressed it from the start.

The issue is that the particular dealership I used here in the GTA would only work on the car if and only if an actual code was thrown, no code or no the coolant light on, no service.

[David655321]

mitko, no i didn't have to wait for it to fail completely. i took it in, they had it for the day, and noticed the coolant wasn't circulating properly due to a partially failing thermostat and replaced it. it sounds like you have the same issue. the service advisor said i caught it before it totally failed. the needle never moved above the middle, and max temp was about 115C i think. now that its fixed, and once it is warmed up, it is usually between 93C and 102C or so, depending on moving, sitting in traffic etc. i wish they would have replaced the water pump too, since the supercharger was off, but they didn't.

Tanner, that totally sucks, that was what I was trying to avoid...getting stuck on the roadside!!