RS3 Heat Failure Linked to Faulty Solar Sensor

Just had the same issue on an Audi S3 (2018). The sunlight sensor malfunction caused the HVAC system to misread cabin temperatures, leading to poor heating performance. The fault detection system showed similar error codes. The repair required replacing both the daylight sensor unit and its wiring harness connector. The original issue stemmed from corroded terminals in the plug connection, which affected the solar sensor readings. This interfered with the automatic climate control calculations. While changing the sensor itself is straightforward, the calibration process needs dealer-level diagnostic equipment to properly integrate with the HVAC control module. Its a critical repair since incorrect sensor data can lead to persistent heating issues and potential damage to other climate control components. The complete fix included: Replacing the solar sensor assembly, Installing new wiring connector, Full system calibration, Clearing fault codes, Testing temperature control across all settings This was not a quick-fix job, as proper calibration is essential for optimal HVAC performance. Getting it done at a certified shop is recommended due to the specialized diagnostic equipment needed.

Thanks for the detailed breakdown of the repair process. I actually dealt with nearly identical symptoms on my RS3 last winter. The fault detection system kept throwing the same error codes related to the HVAC sensor. The heating issues really started causing problems once temperatures dropped. Would you mind sharing what the total repair cost was for your fix? Mine took a decent hit to the wallet but curious if prices vary. Also wondering if youve had any recurring issues with the sunlight sensor or climate control since getting it sorted?

After fixing the solar sensor fault on my S3, everything has worked perfectly. The HVAC sensor readings are now accurate and the heating system responds correctly. The repair was fairly simple, turned out to be just a faulty cable connection to the daylight sensor that needed addressing. Total cost came to 95 Euro for the repair, which included fixing the plug connection and testing the system. Much cheaper than initially expected, especially since no replacement parts were needed. The certified shop diagnosed it quickly as a wiring issue rather than a complete sensor failure. No recurring issues since the fix. The climate control system maintains consistent temperatures and the fault codes havent returned. The solar sensor now properly adjusts the HVAC settings based on sunlight intensity, which was the main problem before. If your symptoms match, might be worth checking the wiring connections first before replacing any components. A loose or corroded connection can mimic a complete sensor failure while being much simpler to fix.

I went ahead and got my RS3 checked at a certified Audi dealer after reading all the feedback. My temperature sensor issue turned out to be more complex than just a wiring problem. The sunlight sensor had completely failed and was sending incorrect data to the HVAC system. The total repair came to 485 Euro, which included: New solar sensor unit, Complete system calibration, Full diagnostic scan, Labor costs for installation The shop completed everything in one day. The fault detection system shows no more errors and the heating now works perfectly. The climate control responds correctly to temperature changes and sunlight conditions. While the cost was higher than expected, having a properly functioning HVAC system is worth it. Definitely learned my lesson about going to certified shops for sensor-related issues. The diagnostic equipment they used quickly pinpointed the exact problem, unlike my previous mechanic who just kept guessing.