Arteon Hybrid Heat Exchanger & AC Failure After Repairs

Had similar problems with a 2017 Passat GTE Hybrid. The cooling system symptoms matched exactly, AC failure combined with dashboard warnings. The root cause was a defective temperature sensor in the heat exchanger that was sending incorrect readings to the control unit. The repair required complete sensor calibration and replacing the AC control module. The heat exchanger itself was functioning properly, but the faulty sensor was causing the system to shut down as a protective measure. While not a major mechanical issue, it required specialized diagnostic equipment to properly identify and resolve. The coolant leak check came back negative, which initially pointed to electrical rather than mechanical problems. Vehicle maintenance records showed no previous cooling system issues, suggesting this was an isolated electronic fault rather than a recurring problem. This is actually a known weakness point in some VW hybrid cooling systems from that generation. The sensor calibration must be done precisely with the correct diagnostic tools, or the problems will return. A qualified shop with hybrid experience should be able to diagnose and repair this fairly quickly with the right equipment. The fix completely resolved both the AC functionality and error codes. No related issues have occurred since the repair was completed.

Thanks for sharing your Passat GTE experience. Your symptoms do sound identical to what Im seeing on my Arteon. Really helpful to know it was a sensor malfunction and not a complete heat exchanger failure. Before I book a shop visit, could you share roughly what the repair cost was for the sensor calibration and control module? Also curious if youve had any temperature gauge issues or other cooling system problems since getting it fixed?

Since getting my Passat GTE repaired, the HVAC system has worked flawlessly with no temperature gauge fluctuations or cooling system warnings. The temperature sensor heat exchanger defect was identified and fixed during the diagnostic process, which was crucial for proper system operation. The total repair came to 980€ for replacing the faulty air conditioning control unit, including the necessary sensor calibration work. The investment was worth it, as the engine cooling and climate control have performed perfectly for the past year. The original sensor malfunction symptoms completely disappeared after the repair. Make sure any shop you choose has experience with hybrid cooling systems, as proper diagnostic equipment is essential for accurate sensor calibration. The temperature readings need to be precisely calibrated to work correctly with the control module.

Thanks everyone, wanted to share a quick update on my Arteon situation. Finally got it sorted at a certified hybrid specialist shop last week. Diagnosis confirmed what you mentioned about the temperature sensor and control module issues. The repair bill came to 1150€ which included a full HVAC system diagnostic, new sensor installation and complete calibration of the cooling system. More than I hoped to pay but less than I feared given the symptoms. The job took about 6 hours total. They showed me the faulty sensor that was causing all the temperature gauge errors. Since the fix, the AC is working perfectly and all dashboard warnings have cleared. No coolant leak issues or other problems have shown up. Really glad I found a proper shop with hybrid experience rather than going back to the previous mechanic. Their diagnostic equipment picked up exactly where the sensor malfunction was happening in the heat exchanger. Thanks again for helping point me in the right direction with this. Would have been lost trying to figure this out on my own.