Audi Q5 Heating Fails Due to Faulty Sunlight Sensor

Having some experience with similar sensor issues, I dealt with this exact problem on my 2017 Audi Q3. The automotive sensor fault symptoms matched yours perfectly, reduced heating and climate control problems tied to a faulty sunlight sensor. The workshop diagnosed a damaged wire connection to the solar sensor unit. The sunlight sensor plays a crucial role in the climate control system, and when it malfunctions, the system defaults to a lower heating output as a fail-safe measure. The repair involved: Complete diagnostic scan, Testing the sensor connectivity, Replacing damaged wiring and connector, Basic sensor calibration, Final system test Total cost was 95 Euro including labor and parts. The fix took about 2 hours and resolved the heating performance issues completely. To provide more specific guidance about your Q5: Are you getting any specific error codes? Does the issue occur more during certain weather conditions? Have you noticed any correlation with direct sunlight exposure? When did the problem first appear? This could help determine if your car sensor issue matches what I experienced and whether you might need similar repairs.

Last service completed at 118327 KM, about 2 months ago. The HVAC sensor fault appeared shortly after that service. I get error code P0538 which points to the solar sensor circuit. Had the diagnostic repeated at two different shops, both confirming a fault in the sensor system rather than wiring. From what I understand, a complete sensor calibration might be needed, not just a basic one. The fault detection system shows consistent errors regardless of weather conditions. One shop quoted 380 Euro for replacement and calibration of the complete solar sensor unit. Would appreciate knowing if others faced similar high repair quotes for sensor replacement.

Based on the error code P0538 and your mileage details, this definitely points to the sensor unit itself rather than the wiring issue I initially faced. After dealing with my simpler wiring repair, I later encountered a complete sunlight sensor failure on my Q3 that matches your situation more closely. The 380 Euro quote aligns with what I paid for the complete temperature sensor replacement and calibration procedure. The higher cost compared to my first repair reflects the need for: New OEM sensor unit, Advanced diagnostic testing, Complete sensor calibration sequence, System integration verification The fault detection system showing consistent errors matches what I experienced with the failed unit. The advanced calibration is necessary because the climate control system needs proper sunlight sensor input to manage heating output effectively. The shop I used confirmed that basic sensor calibration alone wouldnt resolve persistent P0538 codes. They explained the complete unit replacement was unavoidable once the internal sensor components fail. Have you noticed any automatic climate control features working inconsistently along with the heating issues? This would further confirm the diagnosis.

Thanks for all the detailed feedback. After reviewing the responses and comparing symptoms, I feel more confident about proceeding with the complete sensor replacement. My symptoms match exactly what others described, persistent P0538 codes and reduced heating regardless of settings. The 380 Euro quote seems reasonable now that I understand the full scope of work needed. The automatic climate control has been inconsistent, especially the auto-dimming features that rely on the solar sensor input. Getting the temperature sensor replaced and properly calibrated should resolve both the heating performance and related climate control issues. Will book the repair next week since the fault detection system keeps showing the sensor error codes. Better to address it now before winter when I really need the heating system working properly. Thanks for helping me understand that this requires more than just basic calibration to fix the persistent temperature sensor faults.