VW Lupo Sensor Failure Kills Climate Control System

Had the exact same temperature reading issues on a 2004 VW Polo TDI last season. The climate regulation system showed similar symptoms, incorrect sensor diagnostics and complete HVAC sensor failure. The repair involved testing the wiring harness connection to the temperature sensor unit. After running diagnostics, we found corroded pins in the main sensor connector block. The HVAC sensor replacement alone would not have solved it since the entire wiring assembly was compromised. The fix required removing the dashboard trim to access and replace both the temperature sensor and the damaged connector assembly. While not particularly complex for an experienced technician, it was time-consuming due to the dashboard disassembly requirements. This turned out to be a serious issue since driving with malfunctioning climate control sensors can lead to incorrect temperature readings and potential damage to the HVAC system. The faulty sensor diagnostics also triggered multiple error codes which needed clearing after the repair. Consider having a VW specialist check it since they will be familiar with the common sensor issues in this model range. They should first verify if its just the sensor or if theres additional wiring damage like in my case.

Thanks for sharing your experience with the sensor issues and HVAC system fix. Mine shows the exact same symptoms and error codes, so Im relieved its likely the same root cause. Could you share roughly how much you ended up paying for the complete repair including parts and labor? Also wondering if youve had any recurring climate regulation problems since the sensor replacement and rewiring was done? Just want to budget properly and make sure the fix will actually last before taking it to a shop.

Just got my 2004 VW Polo back from the repair shop and wanted to update on the climate control fix. Turns out I was right about the interior temperature sensor being the culprit. The mechanic found a loose cable connection at the sensor unit which was causing the erratic temperature readings. The total repair came to 95€, which covered fixing the faulty connection and testing the climate regulation system. Much cheaper than I expected since no actual sensor replacement was needed, just securing the connection properly solved the issue. Since the repair three months ago, the climate control has worked flawlessly. No more error codes, and the temperature readings are now accurate. The AC turns on normally and the entire HVAC system regulates temperature correctly. The fix was indeed much simpler than initially feared. If your symptoms match what I experienced, theres a good chance its also just a connection issue rather than needing a complete sensor replacement.

Thanks everyone for the advice, wanted to share how my repair went. Finally took my Lupo to a different mechanic who specializes in VW climate control systems. The temperature sensor was indeed the main problem, but there was also a worn wiring harness causing intermittent connection issues. The mechanic showed me how the old HVAC sensor was actually melted slightly at the connector points. Total cost came to 180€, higher than expected but included both the new sensor and rewiring work. The climate regulation is now working perfectly after fixing both issues. No more error codes or incorrect temperature readings. The repair took about 3 hours since they had to partially remove the dash to access all the climate control components. Worth every cent though, the AC works better than it has in years and the interior temperature stays exactly where I set it. Really glad I switched mechanics. This one took the time to explain the entire HVAC system issue and showed me the damaged parts. Much better experience than my previous attempts to get it fixed.