Audi S4 Climate Control Dead: Sensor May Be Culprit

Having some experience with VAG cars, I faced a very similar issue with my 2006 Audi A4. The temperature control symptoms were almost identical, and the climate regulation system showed comparable error codes. After multiple sensor diagnostics at my workshop, they found that the wiring harness connecting to the interior temperature sensor had corroded connection points. The climate control issues were resolved by replacing the damaged wiring and cleaning the connector pins. The total repair cost was 95 Euro, which included the labor for sensor diagnostics and fixing the connection. The temperature sensor itself was actually fine, it was just the connection causing erratic readings in the climate control module. This is a common issue in these models due to their sensor wiring layout. Could you share: Have you noticed if the temperature readings on your display fluctuate out of nowhere? Did the issue start suddenly or develop gradually? Does the manual fan control still work? Which error code specifically appears in memory? This information would help determine if your issue matches what I experienced or if you might be dealing with a different temperature control problem.

Thanks for the detailed response about the wiring harness issue. My vehicle was last serviced at 53690 KM and the HVAC sensor readings do indeed fluctuate out of nowhere on the display. The manual fan control still functions normally, but the error code P0533 keeps appearing during sensor diagnostics. The climate regulation problems started gradually over about two weeks before failing completely. I will have my mechanic check the wiring connections first before replacing any components of the climate control system. Good to know this might be a cost-effective fix rather than needing a full sensor replacement.

This definitely sounds identical to what I experienced with my A4. The fluctuating sensor readings and P0533 code during sensor diagnostics strongly suggest a wiring connection problem rather than a failed temperature sensor. The fact your manual fan control works normally further confirms this diagnosis. When the temperature sensor itself fails, it often affects multiple climate control functions. The gradual development of the issue is also typical of corroding connections rather than sudden sensor failure. A thorough inspection of the wiring harness near the temperature sensor should reveal similar corrosion points to what I found. Make sure your mechanic checks both ends of the harness during the sensor diagnostics, as corrosion can occur at either the sensor or control module connection points. For reference, my climate regulation system has worked flawlessly since the wiring repair, with no temperature control issues in over 60000 KM. The sensor replacement would have cost around 280 Euro, so the wiring fix at 95 Euro was significantly more economical. Just ensure your mechanic applies dielectric grease after cleaning the connections to prevent future corrosion affecting the climate control system.

Thank you for confirming those details about the wiring harness. It seems our HVAC sensor issues are quite similar. I really appreciate the information about your specific repair experience, the 95 Euro fix is much more appealing than a 280 Euro sensor replacement. My mechanic will check the wiring connections this week, focusing on both ends of the harness during temperature sensor diagnostics. The fluctuating readings combined with the P0533 code and working manual controls definitely point toward connection issues rather than a complete climate control system failure. I will make sure they apply dielectric grease after cleaning the connections to protect the temperature control components from future corrosion. I will update the forum once my car is fixed to confirm if the wiring was indeed the source of my climate regulation problems, in case others experience similar issues with their S4.