A5 Thermostat Chaos: Hot and Cold Temperature Swings

Recently dealt with nearly identical symptoms on my A4 2016 2.0T. The engine overheating warnings were triggered by a faulty map thermostat, which was causing inconsistent temperature control. The main issue was the thermostat staying stuck closed, preventing proper coolant flow. The temperature sensor readings were erratic, showing both cold and hot extremes. Initial warmup took about 20 minutes instead of the normal 5-7 minutes. Several warning lights appeared on different occasions. The repair required replacing the thermostat housing assembly along with the temperature sensors. This was not a quick fix, the intake manifold needed removal to access the thermostat properly. While everything was apart, it made sense to check for any coolant leaks and replace a few aging hoses. This is considered a significant repair due to the labor involved and the risk of engine damage if left unaddressed. Engine overheating can lead to severe consequences, so addressing inconsistent temperature control issues promptly is crucial. The symptoms match yours precisely, and the mileage point is typical for these failures. Would strongly recommend having it checked by an Audi specialist who regularly deals with these specific cooling system issues.

Thanks for sharing your experience with the thermostat replacement. Had the exact same issue with my A5 last winter, the inconsistent temperature control was really concerning. Got it fixed by replacing the thermostat housing and a few temperature sensors. The cooling fan would out of nowhere kick in even when the engine was cold. Did you notice any other issues popping up since the repair? Would be helpful to know the repair cost you paid, just to compare if prices are similar. The engine overheating symptoms have completely disappeared for me, but wondering if anyone experienced repeat issues down the line.

The repair resolved all my cooling system issues completely. Since fixing the defective map thermostat a month ago, the engine temperature has remained perfectly stable. No more unusual cooling fan activation or erratic temperature readings. The total repair cost came to 350 Euro, which included replacing the thermostat housing and updating the temperature sensors. This seems to be the standard price range for this type of cooling system repair. The mechanic confirmed that a faulty thermostat was indeed causing the engine overheating problems. The coolant system now works exactly as intended, quick warmup time and consistent operating temperature. The repair was worth every cent considering how critical proper temperature control is for engine longevity. From what the technician explained, these thermostat failures are quite common at our mileage point. The initial diagnosis was spot on about the thermostat being the root cause. If maintained properly, the new components should last the remainder of the cars life without needing replacement again.

Wanted to close the loop on my thermostat saga. Finally got it fixed last week and the experience was actually better than expected. Found a specialized shop that diagnosed and fixed everything in one day. The water pump and several temperature sensors needed replacement along with the thermostat. The cooling system diagnosis showed the old thermostat was completely stuck, causing those weird temperature fluctuations. Total bill came to 420 Euro, bit more than others mentioned but they did a thorough job. The cooling fan now operates normally and the engine warms up properly in about 5 minutes. No more overheating warnings or temperature control issues. The mechanic walked me through everything they found and replaced, which really helped rebuild some trust after my previous bad experience. If anyone else runs into similar symptoms, definitely get it checked right away. The repair was straightforward and completely solved the problem. Car runs perfectly now and temperature stays exactly where it should.