A7 Hybrid Cooling System Chaos: Fix Guide Needed

Recently dealt with nearly identical symptoms on my 2018 Audi A6 Hybrid. The cooling system showed similar behavior, prolonged warm-up followed by rapid overheating. Turned out the map thermostat was failing, causing incorrect temperature readings and improper coolant flow regulation. The thermostat would stick either open or closed, preventing proper engine temperature control. This caused the engine management system to receive incorrect temperature data, leading to poor performance and potential engine stress. During repair, we found minor coolant leaks around the thermostat housing. The entire thermostat assembly needed replacement, along with a cooling system flush to remove any debris. The water pump was also inspected as these issues often appear together, but it was functioning properly. This was a serious issue requiring immediate attention, as continued operation risked engine damage. The cooling fan was cycling irregularly due to the misread temperatures, another clear symptom of thermostat failure. Would strongly recommend having this checked soon, as these symptoms typically worsen quickly in hybrid systems due to their complex cooling requirements.

Thanks for sharing your experience. Your symptoms sound exactly like what I went through. The temperature control issues with these hybrids can be tricky. My cooling fan was also acting weird before the fix. After getting it repaired, all temperature issues cleared up and the engine has been running perfectly. Really curious about what you ended up paying for the repair. In my case the temperature sensor also needed replacement which I wasnt expecting. Did you have any other issues pop up since the repair was done? Would be helpful to know if I should watch out for anything specific with the engine overheating protection system.

Thanks for following up. Glad to hear you got it fixed. I had my A6 repaired about 3 months ago, and the main issue was indeed the defective map thermostat in the cooling circuit motor. The total repair cost came to 350 Euro, which included a full system inspection and coolant flush. Since the repair, the temperature sensor readings have been spot-on, and the cooling fan operates normally. The engine now warms up consistently and maintains proper operating temperature, even during extended drives. The coolant system has been working flawlessly with no leaks or irregular behavior. No additional issues have surfaced since the fix. The cooling system maintains stable temperatures across all driving conditions. Just keep an eye on your coolant levels during routine maintenance, its good practice with these hybrid systems. Regular coolant system checks can help catch potential problems early. If you notice any changes in engine temperature behavior or cooling fan operation, best to have it checked right away. But with the new thermostat installed, you shouldnt experience those overheating issues again.

Thanks for the advice. Finally got around to getting it checked out at a different shop. The mechanic found the thermostat housing was cracked, causing the coolant leak and temperature control problems. The repair cost 450 Euro including parts, labor, and a complete cooling system flush. Pretty relieved it wasnt anything more serious. The car now warms up normally and maintains steady temperature, even on longer drives. The cooling fan operates properly too. Much better experience with this new mechanic who took time to explain the entire issue. For anyone facing similar problems, dont wait around like I did. These cooling system issues can get worse quickly. My engine now runs perfectly and the temperature gauge stays right where it should.