martinkoehler1

GLS Hybrid Error Codes and AC Issues

My 2021 Mercedes GLS hybrid is throwing some codes and acting up. The error memory says there's a defective temperature sensor in the heat exchanger. I'm also getting an error message on the speedometer, and the AC won't kick on at all. Mileage is just under 8000 km. Could this be a sensor malfunction? Thinking it might be the AC control unit. Has anyone else run into this? What's involved in sensor calibration for these new HVAC systems?

4 comment(s)

Sounds frustrating. My experience was similar but on a very different car - a 2018 Volvo XC60. My cooling system was acting up, and it turned out to be a faulty temperature sensor. The symptoms were a bit different, but it also affected the HVAC system. Did the error codes point specifically to the sensor, or is it more general?

The error codes are pretty specific about the temperature sensor in the heat exchanger being the problem. Do you remember if replacing yours involved a lot of messing around with the entire cooling system, or was it a relatively straightforward sensor replacement?

In my case, it ended up being more involved than I initially thought. They had to drain and refill the cooling system and then perform some kind of calibration after the sensor replacement. Honestly, it was a bit beyond my comfort level, so I just let the workshop handle it. For a complex hybrid cooling system like yours, I'd strongly advise going to a specialist.

Thanks. Sounds like a trip to the workshop is unavoidable. Just got a quote for around 980€, apparently, the air conditioning control unit is also defective. I appreciate you sharing your experience. Helped me mentally prepare for this.

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