S7 Cooling System Shows Mixed Temperature Signals

I faced nearly identical symptoms with my 2012 Audi S5 last winter. The cooling system issues started with slow warm-up times and unusual overheating warnings. After thorough diagnostic testing, the problem was traced to a defective map thermostat in the thermostat housing. The map thermostat was stuck in a partially open position, preventing proper temperature regulation. This caused both the extended warm-up periods and the overheating issues. The cooling fan would activate erratically, trying to compensate for the faulty temperature readings. The repair required replacing the complete thermostat housing assembly since the map thermostat is integrated into it. During the service, we also found a minor coolant leak from the housing gasket. The water pump was inspected and tested fine. This was a significant repair that required specialized diagnostic equipment to properly identify. The symptoms you describe match the classic signs of a failing map thermostat, which is a known weak point in these engines. Delaying the repair could lead to more serious engine temperature management issues. The fix completely resolved both the warm-up and overheating problems, and the engine now maintains stable operating temperatures.

Yes, those symptoms you described sound exactly like what I went through! It began with similar temperature control problems in my S7, the engine overheating warnings followed by trouble warming up. I got mine fixed about 8 months ago and the mechanic confirmed it was indeed a faulty thermostat plus a worn temperature sensor they discovered during inspection. Would you mind sharing what the repair ended up costing you? My bill came to around 850 Euro including parts and labor, though prices might vary. Has your cooling system been behaving normally since the fix? I had to return once because of a small coolant leak they missed initially, but after that everything has been running perfectly.

Had my thermostat housing replaced about 8 months ago, cost was 350 Euro total including parts and labor. The temperature sensor in the coolant system was working fine in my case, so just needed the map thermostat replacement. Since fixing the defective thermostat cooling circuit, the engine temperature control has been perfect, no more overheating warnings or slow warm-up issues. The water pump and rest of the cooling system checked out fine during inspection. A proper diagnosis with specialized equipment was key to identifying the exact problem. The repair shop did a thorough job testing the complete temperature control system to ensure there were no additional issues or leaks. This seems to be a common failure point in these engines, but once properly fixed, it typically resolves all the temperature-related problems. Mine has been running at stable temperatures for 8 months now with zero issues. The 350 Euro repair cost was worth it to prevent potential engine damage from continued overheating.

Based on my experience at the mechanic, I can confirm it was definitely the thermostat causing all those temperature control issues. The symptoms in my car matched yours exactly. After weeks of frustration with unusual overheating warnings and slow warm-ups, I finally took it to a specialist shop. The mechanic found both a faulty thermostat and a worn temperature sensor during their inspection. The total repair came to 850 Euro, which included replacing both parts and a thorough cooling system check. They had to bring me back once to fix a small coolant leak they missed initially, but they handled it professionally at no extra charge. Its been 8 months since the repair and my S7 maintains perfect operating temperature now. The water pump and rest of the cooling system are working great. Looking back, I should have addressed the problem sooner, but at least its sorted now. Definitely worth the investment to prevent more serious engine damage.