Audi A5 Heater Failure Points to Faulty Water Valve

I dealt with a nearly identical issue on my 2015 Audi A4 last winter. As someone with moderate DIY car maintenance experience, I initially tried diagnosing it myself but ultimately needed professional help. The symptoms matched exactly what youre describing, weak cabin heat and an error code related to the heater core system. The cause was indeed a faulty water valve connection that disrupted proper engine coolant flow to the heater core. The repair involved: Testing the engine coolant circulation, Replacing a damaged connector to the water valve, Recalibrating the valve control unit, Full system check to ensure proper heater core function Total cost was 95 Euro for parts and labor. The fix took about 2 hours at my regular workshop. Since then, the heating system has worked flawlessly. To provide more specific advice for your case, could you share: The exact error code showing up? Does the heat fluctuate or is it consistently weak? Have you noticed any engine coolant level changes? Any engine overheating warnings? These details would help determine if youre facing the same underlying issue I had.

Thanks for the detailed input. At 180528KM on my A5, I checked and the engine coolant level is normal with no engine overheating warnings. The heat consistently stays weak regardless of temperature settings. The error code is P0597. Had my last service 3 months ago where they did a cooling system check, but this issue started just recently. The automotive valve seems to make a clicking sound when adjusting temperature, which wasnt there before.

After seeing your latest details, it sounds even more similar to what I experienced. That clicking from the automotive valve is exactly what mine did before failing completely. The P0597 code typically indicates an issue with the thermostat heater control circuit, but in my case and likely yours, it was actually the water valve causing the system to misread. Since your cooling system was checked recently and the engine coolant level is good, this strengthens the case for a failing valve assembly rather than a broader cooling system issue. The consistent weak heat output matches my experience too, it is a classic symptom of the valve not properly regulating flow. Important note, when my shop replaced my faulty valve, they found the original part had developed internal wear that caused the clicking. The new valve design apparently has better durability. If you do need a replacement, make sure they use the updated version. My repair ended up being straightforward. They: Replaced the water valve assembly, Cleared the error codes, Ran a full heating system test cycle While waiting for repair, try not to constantly adjust the temperature controls, as this can cause additional wear on the already struggling valve mechanism.

That error code definitely helps narrow things down. Looking at the symptoms, I want to get this resolved before winter hits full force. With the clicking noise from the automotive valve and weak heat output, it seems like a straightforward fix based on your experience. The fact that my cooling system check was clean 3 months ago but problems started recently makes me feel better, likely just the valve wearing out rather than a bigger heater core issue. And since theres no engine overheating or coolant level problems, that supports this theory. I will schedule an appointment and request they check the water valve assembly first, making sure to use the updated part you mentioned. Really helpful to know about the potential internal wear causing the clicking, will mention this symptom to the mechanic. Thanks for sharing your repair details. Having this information helps me feel more confident about what to expect at the workshop. Will update once its fixed in case anyone else runs into similar heating system troubles with their A5.