2012 S4 Coolant Issue Car Overheating

[audifan22]

I have a 2012 6 speed S4 stock with just exhaust, and 20k miles (oil changes every 5k miles), and today as I was driving normally, the coolant light came onto the screen and told me to shut the car down immediately. I pulled to the side of the road and noticed that the engine temperature was very high. When I turned the car off the engine area was pretty loud winding down.

I let the car cool off for 5 minutes and looked at the coolant level, it was between the min and max line, so it doesn't seem like its a leak. I waited 15 minutes and drove back home 3 miles...towards the end of the drive the engine temperature was 3/4 Hot instead of in the middle of the C and H.

What could the problem be? I am bringing my car to the dealership on Monday for them to take a look, and since I'm still under warranty I guess it doesn't really matter, but I would still like to know for my own knowledge if this is common and what is causing the issue? Thanks guys!

[isles1]

Could be a bad thermostat. But will all the electronics in cars these days, it could be a bad sensor. I'm sure the dealer will let you know what the ultimate fix is.

[Geri1310]

I just got this same issue, any updates on what was the problem and did warranty cover it?

[A4 Joe]

Bad thermostat. Same thing happened to my 2012 S4. Fatal flaw in design of the thermostat. Has happened to many S4 owners here.

[audistealth]

Bad thermostat. Same thing happened to my 2012 S4. Fatal flaw in design of the thermostat. Has happened to many S4 owners here.

Um, that was fixed for 2012. The broad tstat issue is <= 2011.

[A4 Joe]

Um, that was fixed for 2012. The broad tstat issue is <= 2011.

Um... I don't think so. This is exactly what happened to my former S4 which was a 2012. I have seen more than one post from cars after 2011 with this same problem. A junk plastic thermostat hidden under the supercharger is simply a bad design.

[Geri1310]

thanks for the quick response !!

I also found another thread with more info on this issue seems well known after all.

[AKPS4]

I also thought this was fixed for the 2012's and did not remember seeing anyone else with a '12 with this issue, guess I was wrong.

Damn, thought i was in the "bulletproof" MY club lol.

[tanklee]

thermostat. ive replaced a bunch of 2012 thermostats.

[audistealth]

Well fuck, I'm out of warranty and have a ticking time bomb for a tstat.

[chaos2984]

Well fuck, I'm out of warranty and have a ticking time bomb for a tstat.


Hell if you need one I can do it for you. I have all the special tools if needed. I did all the work on my B5 from timing belt to replacing leaking oring from the coolant tubes under the intake manifold. A t-stat will be no issue for me and i can't be to far from you.

[audistealth]

Hell if you need one I can do it for you. I have all the special tools if needed. I did all the work on my B5 from timing belt to replacing leaking oring from the coolant tubes under the intake manifold. A t-stat will be no issue for me and i can't be to far from you.

Not yet, but I did think it was solved for 2012. If you're a tech in my area, which dealer/Indy are you? I already paid for AC+, and have a good relationship with my SA and SM.

[chaos2984]

I use to work for JBA Chevy Mitsu as a mitsu/chevy tech for 7 years. I had all my ASE's not like that matters they are a joke anyways. I switched jobs and work for Cummins Power Systems due to internal dealership politics. But I owned a B5 and B7 and did everything to them myself. I Did stage 3 to my B5 s4 and yanked the engine and everything. I had a side shop i had access to for a lift to pull the engine and such. But I have a work truck for my new job and have all my tools with me.

[Dr GP]

T stat has been a persistent issue with these cars. Even if it has been replaced, it can and has failed again for some.

[chaos2984]

Whats going on with the t-stats. With the invention of the ecm programing having to watch coolant temp and how long it takes to get up to operating temp. they have done something to the t-stats and working as a technician and I have seen them fail a lot more. But they are failing and sticking open. I haven't seen them fail and stick closed. Are they sticking closed on the S4 or are they sticking open. I have a 06 for explorer that the t-stat has failed and sticks open and in the winter the cel comes on for the t-stat but goes off in the summer time. Im just to lazy to change it since it doesn't stick closed. And i don't drive it that much. Usually on a normal summer day the sticking of the t-stat open will not hinder anything you might run a few degrees under normal operating temp but nothing crazy. in winter it won't even reach operating temp.

[A4 Joe]

Fail closed....not a good deal. I came close to burning up the motor on my 2012.

[chaos2984]

man that sux. haven't seen them fail closed in awhile unless the car is really really old pre 00 era.

[IanCH]

As others have said, this is the tstat failure mode and all cars are susceptible as the part hasn't changed through b8.5 IIRC.

On the other side, I have a coolant temp sensor go bad the other day and the failure mode is different than T-stat. The car doesn't immediately overheat, but the temp gauge on the dash doesn't work right and reads low. This causes the car to attempt to heat the engine up and can eventually lead to overheating. If you see it, get to the nearest garage and the sensor costs about 30-40 dollars and is a 10 minute replacement right at the front of the supercharger.

[MYFASTA4]

and if we delete the t-stat?

[chaos2984]

and if we delete the t-stat?

you deff dont want to do that. The engine will never heat up at all and you will have a constant cel light on. And you will get crappy gas milage as well.