Audi S8 Parking Heater Failure: Common Repair Guide

As someone with some experience working on Audis, I had a similar issue with my 2012 Audi S6. The auxiliary heater symptoms matched yours exactly, main heating system worked fine, but the auxiliary heater was completely non-responsive. After checking the temperature sensor and ruling out a coolant leak, the workshop diagnosed a defective glow plug in the auxiliary heater system. The heating system components in these models are quite similar, and this is actually a known weak point. The repair involved replacing the glow plug assembly and performing a system reset. Total cost was 440 Euro including diagnostics and labor. Since the fix, the auxiliary heater has worked flawlessly for over two years now. To better assist with your specific case, could you share: Current mileage on your S8, When did you first notice the issue, Any warning messages on the display, Whether you hear the auxiliary heater trying to start, Have you checked the heater core for signs of damage This information would help determine if your issue matches the common failure pattern in these models.

Just had my 180135 KM service done last month. You described this perfectly, the climate control and main heater work normally, but complete silence from the auxiliary unit when trying to activate it. Getting error code P1899 from the climate control module. The auxiliary pump makes no sound at all when attempting to start. Will probably need to get it checked professionally as it seems to match the glow plug failure pattern you mentioned. Thanks for sharing your experience with the repair costs and process.

Thanks for the mileage info and error code, that P1899 is exactly what I saw on my S6 before the repair. The silent auxiliary pump is another telling sign that confirms my initial suspicion about the glow plug assembly. At that mileage range, its quite typical for the auxiliary heater components to start failing. The ventilation system and main climate control working normally actually helps narrow down the issue, as it rules out problems with the central heat control module. Since getting my glow plug replaced, I made sure to activate the auxiliary heater at least once every few weeks during warmer months to prevent similar issues. This regular cycling seems to help maintain the system components. One tip, while youre at the workshop, have them check the auxiliary heater fuel lines and connectors too. In my case, they found minor wear that could have caused issues later. The additional inspection only added about 30 Euro to the total repair cost but was worth the peace of mind. Let us know what the workshop finds. Would be interesting to see if its the same glow plug issue affecting these models.

Thanks everyone for the detailed feedback. My S8 is now booked in for next week. After hearing about the common glow plug issue and seeing how the symptoms match exactly, I feel more confident about what to expect. Will make sure to mention checking those fuel lines and connections too, good call on preventive maintenance while its being worked on. The auxiliary heater definitely sounds like the same problem, especially with that P1899 code and complete silence from the pump. Really helpful to know the repair costs were reasonable at around 470 Euro total including the extra inspection. Its reassuring to hear the fix has been reliable long-term for others. Will post an update once the workshop confirms the diagnosis and completes the repair. Appreciate all the specific technical insights about the temperature sensor, ventilation system, and potential failure points. This will help me have a more informed discussion with the technician.