09mazda6

11 a6 3.0 w @ 122k miles. Water pump and thermostat replaced by Audi at @ 30 with original owner under TSB. I drove 2.5 hours last weekend on highway - no issues. Car was parked for 1 hour and then started back home. 90% highway - mid 70 mph and a little over an hour in - I notice that my oil temp was moving up, then looked to left and notice that coolant temp gauge was going up and in what seemed like a few seconds but was likely a few moments oil temp was 240s and red stop car pull over light came on. I was pulling over, cranking heat and opening windows to pull off heat. Car quickly got to normal coolant temp but oil temp was high but coming down. Pulled off at upcoming exit. Car still running - coolant level up - nothing leaking - DS fan was going like full tilt. PS fan no running at all. Things continued to cool off and I drove home on Rt#1 (under 50 mph) with heat cranked, sunroof open and temps all @ normal.

My friend with ross-tech cable is out of town so I can't run scan til later this weekend. Tried by very basic OBD reader. No codes were thrown/showing - CEL never came on. Coolant level was a hair under minimum but it had been @ minimum prior. Oil for all it dealt with seems ok from smell/feel. Since then drive very carfully to work and back (7 mile each way with only 1 mile of highway speed in the middle) - sometimes with heat cranked other times with no heat on to see if I can cause temps to rise. Thing have been fine with two exceptions: one time coming home - pulled into garage and both fans started running at max speed just as I pulled in. let car run, temps all good fans slowed and shut car off. that seems to rule out that the PS fan was dead which I had thought might be the issue initially. Another time I had to travel further @ highway speed and temps went up and I had to pull heat to keep things going but other times on literally the same exact drive, temps stay normal. so mu suspects @ this time are are Thermostat, Coolant Temp sensor or Fan control module. the last two seem fairly easy to repair while the thermostat would require removing the S/C etc. welcome your thoughts or experience with this. I will try to run VCDS when friend returns but if no codes thrown not sure it's going to tell me much and that also leads me to think the thermostat is the issue as the other two being electronic seem to have codes associated with them that i would see.

cross-posted on AZ

JustinTucker

Well, as it turns out my 2015 Audi S5 is in the shop as we speak getting both cooling fans replaced. Overheated on me a few times. Water pump was fine, thermostat checked out. The fans stopped turning on. Quite unusual in my opinion for a car with 18k miles. However, stop and go traffic for those 18k and in the heat of Miami? Probably still shouldn't make those go like that. Audi is one of the most popular cars in Miami, so...

That said, check out the fans. If they are both running, then it could be fine and you are looking more like another thermostat. But, one thing to consider, which I didn't before, one fan may be running all the time and over working. That's what happened to mine. One fan went out and the other ended up going out because it was running all the time on like "overdrive". I could hear it, but sometimes just thought it was a mix between the SC and A/C.

Good luck!

09mazda6

Thanks for the suggestions - I'm going to check those out too but when they do go on they both run but at a very high level (like when I drove to VA in 100 temps this summer) so I suspect that if/when the thermo does allow coolant to flow it's very hot and so fans go into hyper-drive. Yet another reason to fix thermo as eventually all this high RPM fan could end up burning those out as well.