Faulty Temperature Sensor Disables Multiple RSQ3 Systems

Had a similar issue with a 2012 RS3 (which shares many components with yours). I have some experience working on these cars and dealt with this exact vehicle temperature sensor problem last winter. The symptoms you describe match what I experienced, multiple temperature-dependent systems acting up due to faulty sensor readings. My outside temperature sensor was sending incorrect data to the control unit, affecting various systems. In my case, after initial troubleshooting, the workshop found a damaged wire connection to the sensor. The cable insulation had worn through, causing intermittent contact. The repair involved replacing the wiring harness section and the sensor calibration. Total cost was 95 Euro, which included diagnostic time and parts. Before suggesting specific fixes, could you share: Are you getting any specific error codes? When did these issues start occurring? Does the temperature display show any reading at all, or is it completely blank? Have you noticed if the problems get worse in wet conditions? The sensor malfunction can stem from various causes, from simple connection issues to complete sensor failure. Your RS model likely uses a similar system to mine, but knowing these details would help narrow down the potential solutions.

Thank you for sharing those details. Yes, getting error code P0073 which points directly to the vehicle temperature sensor circuit. Issues started after heavy rain last week. Temperature readings are erratic, jumping between -40 and +80 out of nowhere. Had latest service at 175000 KM. Currently at 179330 KM. Looking back at service records, the car temperature sensor was never replaced. Based on the symptoms and error code, seems the sensor unit itself might need replacement rather than just wiring fixes. Will start with checking connectors for corrosion though. Would it be worth testing the outside temperature sensor before replacing? Not sure if standard OBD tools can verify sensor readings or if special equipment is needed.

Based on the error code P0073 and those erratic temperature readings after rain exposure, this definitely confirms my initial suspicion about the vehicle temperature sensor being faulty. My situation was quite similar, though my readings were completely stuck rather than jumping around. I initially tried cleaning the sensor connections, but in these cases unusual temperature fluctuations usually indicate internal sensor failure. The sensor diagnostics I ran with a basic OBD scanner were somewhat helpful, but the specialized diagnostic equipment at the workshop provided much clearer data about the sensor malfunction. After dealing with my sensor issues, I learned its better to go straight for temperature sensor replacement rather than attempting temporary fixes. The sensor calibration process after installation was essential, without proper calibration, the new sensor can show similarly erratic readings. For reference, my complete repair including the new sensor, installation, and calibration ended up costing 220 Euro. The sensor diagnostics revealed the internal circuitry was damaged, likely from water intrusion similar to your case. Given your mileage and the fact its the original sensor, replacing it would resolve multiple issues at once, the AC function, washer nozzles, and mirror heating should all return to normal operation with a properly functioning sensor.

Going to take your advice and opt for a complete outside temperature sensor replacement rather than trying partial fixes. The jumping readings and error code P0073 seem pretty conclusive about sensor failure. Will book the car in next week and make sure they do proper sensor calibration after installation. Good to know the rough cost estimate of 220 Euro for the complete job. Makes sense that the original sensor could fail after this distance, especially with the recent water exposure. At least this should fix all the temperature-dependent systems at once. Just hope the temperature monitoring system returns to normal after replacement. Really miss having working AC and heated mirrors. Thanks for confirming this matches your experience, helps knowing its a known issue with a clear fix rather than something more complex. Will update once the sensor replacement is done, in case others run into similar symptoms with their temperature sensor in the future.