G Klasse climate control problems

Sounds like a plausible diagnosis. The interior temperature sensor is usually a thermistor, a resistor that changes resistance with temperature. If the cable or plug is defective, the resistance signal will be incorrect or non-existent, causing your climate issues. Have you checked the sensor's wiring and connector for damage or corrosion? Even a visual inspection can sometimes reveal the problem.

Thanks for the thermistor explanation! I did a quick visual check, but I'm not sure what to look for beyond obvious breaks. Where is the temperature sensor located in the G Klasse? Knowing the location will help me investigate the cable and plug connection. Is sensor replacement hard?

Given your description and the error code, it points to the temperature sensor or its wiring. Considering you're not comfortable with electrical diagnosis, and sensor replacement could involve some fiddling, it might be best to take it to a workshop. They can pinpoint the fault and perform the sensor replacement if needed.

Thanks, I appreciate the advice. I took it to a local shop, and you were spot on. It was the interior temperature sensor, or rather, a loose connection. They fixed the cable and plug connection. The sensor replacement wasn't necessary. Total cost was 95€, and the climate control is working perfectly again!