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andreaskoch2

VW Touareg TDI Temperature Sensor Issues and AC Failure

Looking for advice on my 2016 VW Touareg TDI that recently started acting up. The temperature sensor seems to be causing multiple issues, getting an error message in the speedometer display, stored fault codes, and the AC wont turn on at all. Pretty sure its related to a faulty heat exchanger temperature sensor, but want to confirm before replacing parts. Has anyone dealt with similar symptoms? Particularly interested in hearing what the actual fix was and rough repair costs. Getting it checked at a shop soon but would appreciate input from those whove been through this before.

Summary of the thread

A 2016 VW Touareg TDI is experiencing issues with the temperature sensor, leading to error messages, stored fault codes, and AC failure. The problem is suspected to be related to a faulty heat exchanger temperature sensor. A shop diagnosis revealed a small coolant leak near the sensor connection, affecting the engine cooling system. The recommended solution is to replace the entire heat exchanger unit to prevent worsening of the leak and ensure reliable temperature readings.

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4 comment(s)

hermannfrank9

I faced a similar issue with my 2014 VW Tiguan TDI last summer. Based on some experience working with HVAC systems and sensor malfunctions, these symptoms sound very familiar. The temperature gauge was showing incorrect readings, and the AC control unit stopped responding completely. After multiple diagnostic attempts, the workshop confirmed it was indeed the AC control module that had failed, not just the temperature sensor as initially suspected. The repair involved: Complete diagnostics of the HVAC system, Replacement of the control unit, System recalibration, Coolant leak check and top-up, Final testing of all AC functions Total cost came to 980€ for parts and labor. The repair took about 6 hours to complete, but the vehicle has been running perfectly since then with no temperature-related issues. Before suggesting specific solutions, could you provide: Exact error codes showing up, Whether the coolant level is normal, If you notice any unusual sounds when trying to operate the AC, How long the problem has been occurring, If the issue appeared gradually or suddenly This information would help determine if your case matches what I experienced with my vehicle maintenance issues.

andreaskoch2 (community.author)

Had my car into the shop yesterday for diagnosis at 76003km. They found the heat exchanger had a small coolant leak near the sensor connection, which was causing erratic temperature readings. The engine cooling system wasnt working properly because of this. Got the sensor calibration done but they recommended replacing the entire heat exchanger unit since the leak could get worse. Appreciate the detailed insight into your AC control module issue, but seems my problem might be more straightforward. Did you notice any coolant loss before your control unit failed? Wondering if I should get a second opinion before authorizing the full heat exchanger replacement.

hermannfrank9

Thanks for the update on your Touareg. With my Tiguan repair experience, I can definitely relate to wanting confirmation before a major repair. Looking back, I did not notice any coolant loss before my control module failed. Your situation with the leaking heat exchanger sounds quite different from what I experienced. When there is an actual coolant leak near the temperature sensor, replacing just the sensor would likely be a temporary fix at best. The small leak you mentioned can definitely cause unreliable temperature sensor readings and affect the engine cooling system performance. Given that the leak is already confirmed, I would actually agree with the shop recommendation. In my years working with VW cooling systems, small leaks near sensor connections tend to worsen over time due to constant temperature cycling and pressure changes. The engine cooling system is too critical to risk running with a known leak. While sensor calibration might improve readings temporarily, the underlying leak will continue causing issues with temperature monitoring and potentially lead to more serious problems. What did they quote for the complete heat exchanger replacement? For comparison, when I had other cooling system work done previously, parts and labor typically ran between 600-900€.

andreaskoch2 (community.author)

Thanks for sharing those details about the Tiguan cooling system issues. After getting your input and the shop diagnosis, Im feeling more confident about moving forward with the heat exchanger replacement. They quoted 850€ for the complete job, which seems in line with what you mentioned. The coolant leak is minimal right now, maybe losing about 100ml per month. But the temperature sensor malfunction is already affecting vehicle performance, and I dont want to risk more serious engine cooling system problems down the road. Think Ill schedule the repair for next week. Will probably have them do a full cooling system flush while theyre at it since the vehicles at 76000km anyway. Better to address everything properly now rather than dealing with bigger issues later. Really appreciate everyone sharing their experiences with similar temperature gauge and sensor problems. Having this information helped me make a more informed decision about the repairs.

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VW

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TOUAREG