Problems with fan, heating/cooling and warning light in 2015 Mercedes ML-Class Diesel

Hey, I had a similar problem with my 2013 Mercedes GL class diesel. I'm not a mechanic though, just a guy with some experience in troubleshooting cars. I then confided in my garage, who recognized the problem immediately. The 'wiring harness defective' was the diagnosis. Had to pay 155 euros for it. Did the dealer read out any error codes? Could be helpful in finding the cause. What maintenance work has been carried out recently? This information will help me to better classify your problem.

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Thanks for the info. So at my last inspection at 93661 km, nothing special was actually done, just the usual things like oil change and filter replacement. Unfortunately, the dealer didn't read out any error codes because he thought that the sensor was probably not calibrated correctly. But unfortunately that didn't help much. I'll have the wiring harness checked. That wouldn't be a problem for €155. Thanks for the tip!

(Translated from German)

No problem, you're welcome! My experience is exactly the same - always pay attention to the little hints. Maybe it really is a calibration issue, or maybe it's a faulty wiring harness. Good luck with the troubleshooting and hopefully it won't be too expensive to fix. Let me know when you know more. Maybe your case can help others who have the same problem.

(Translated from German)

Thank you for the quick reply! That is very helpful advice. I also hope that the problem will be solved soon. When I have solved the problem, I will definitely let you know. Thanks again and have a safe journey!

(Translated from German)