SQ7 Heater Failure: Water Valve May Be The Culprit

Had the same heating issues on my 2019 Audi S7 with the 4.0L engine. The symptoms matched exactly, weak heat output despite normal coolant levels. Initial diagnosis revealed a faulty heater core valve causing improper coolant flow through the system. The car valve was sticking in a semi-closed position, restricting hot coolant flow to the heater core. This required removing parts of the dashboard to access the valve assembly. What seemed like a simple valve issue turned into a more complex repair involving the entire heater core system. A coolant leak was also discovered near the valve connection points, which explained why the coolant level appeared normal despite the system not functioning properly. The repair involved replacing both the valve assembly and associated seals to prevent future engine overheating issues. This was a serious repair that required specialized diagnostic equipment to properly identify the root cause. Given the symptoms and model year of your SQ7, would strongly suggest having it properly diagnosed despite past dealer experiences, as continuing to drive with restricted coolant flow could lead to more extensive damage. The heating system in these engines is quite complex, what starts as a simple valve issue can indicate broader cooling system problems that need addressing.

Thanks for sharing your S7 experience. Your case sounds identical to what I am experiencing with my SQ7 heating issues. Already scheduled a dealership appointment after reading about potential engine overheating risks if left unchecked. How much did the entire valve and heater core repair cost you? Also curious if the car heating has worked flawlessly since the fix or if you noticed any other cooling system problems afterward?

I got lucky compared to what I initially feared. The mechanic found the issue was simply a faulty wire connection to the valve control unit, not a complete heater core failure like we first suspected. The total repair came to 95 Euro for fixing the cable connection that was causing the valve blockage. The heating has worked perfectly since the repair, maintaining consistent temperature and proper coolant flow through the cooling system. No engine coolant issues or valve problems in the 15000km since the fix. The engine temperature now stays stable even during long drives in cold weather. Looking back, the weak heat output was definitely from the water valve not getting the proper electrical signal to fully open. Much simpler fix than replacing the entire heater core assembly, which would have cost significantly more. The cooling system is working as designed now that the valve can properly regulate coolant flow. Hope your repair turns out to be equally straightforward.

After reading your advice, I decided to take my SQ7 to a different dealer branch. Turned out the heating problem was caused by a clogged heater core valve, similar to what you experienced. The mechanic found debris restricting coolant flow through the cooling system. The repair cost came to 320 Euro including a full system flush and new engine coolant. They also replaced some worn seals around the car valve assembly. Pretty reasonable considering I feared a complete heater core replacement. Car heating works perfectly now, strong warm air and no more error codes. The engine temperature stays consistent even on longer drives. Really glad I got it checked instead of waiting for potential problems to develop. Thanks again for pushing me to get it properly diagnosed despite my hesitation with dealers. Sometimes finding the right shop makes all the difference.