VW Transporter Trans Failure Linked to Radiator Issues

Had the same symptoms on a 2017 VW Tiguan 2.0 TSI. The transmission issues were traced to a faulty pressure sensor connection at the radiator-transmission cooling circuit. The cooling fan was running constantly, indicating the system was trying to compensate for perceived overheating. The root cause turned out to be corroded wiring at the pressure gauge connector, leading to incorrect readings. This triggered the transmission control unit to enter limp mode as a protective measure. A leak detection test confirmed no actual coolant leak existed, it was purely an electrical connection issue. The fix required replacing the wiring harness section and pressure sensor assembly. While not a major mechanical problem, leaving it unfixed could have led to transmission damage due to improper cooling control. The grinding noise you describe matches what happened in my case, the transmission was unnecessarily downshifting and holding lower gears based on false pressure readings. Getting this diagnosed and repaired at a transmission specialist is important since general mechanics sometimes misdiagnose it as internal transmission failure. Make sure they check the electrical connections and perform a proper pressure sensor diagnostic before attempting any transmission repairs.

Thanks for sharing your experience with the pressure sensor issue. I had very similar symptoms with my VW Transporter last year. The cooling system diagnosis matched what you described. The transmission went into limp mode and the cooling fan was running non-stop. Would you mind sharing how much the repair cost in your case? I am curious if you have experienced any other cooling system or radiator repair issues since getting it fixed? My mechanic quoted a significant amount and I am trying to get a better sense of typical repair costs for this type of problem.

Thanks for asking about the costs. Since getting the radiator oil pressure sensor fixed at 95€, the transmission has worked flawlessly. The repair was straightforward, just needed a new cable connection at the pressure gauge assembly. No coolant leak or other cooling system problems have occurred in the months since. The constant fan running and limp mode issues disappeared completely after the repair. My mechanic confirmed through leak detection tests that the cooling circuit was functioning normally, it was purely an electrical connection causing false readings. That price seems reasonable compared to what some shops charge for major transmission work. If your quote is significantly higher, you might want to get a second opinion from a shop that specializes in VW cooling systems. The car overheating symptoms and transmission behavior often make mechanics assume worst-case scenarios, when it could just be a simple sensor issue like in our cases. Just make sure they verify the actual pressure readings and electrical connections before doing any extensive repairs. A proper diagnostic will save money in the long run.

After getting multiple quotes, I finally got the repair done at a different shop that specializes in VW transmissions. The total cost came to 120€ for replacing the pressure sensor and fixing the wiring harness. Much better than the 800€ quoted by the first mechanic who thought it needed major transmission work. The specialist used proper leak detection equipment to diagnose the exact issue with the radiator cooling circuit. They showed me the corroded wiring that was causing the false pressure readings. The repair took about 2 hours and the transmission has been shifting perfectly since then. No more grinding noises or warning lights. The cooling fan now operates normally and the transmission temperature stays stable. It was such a relief to avoid an unnecessary transmission overhaul. Getting a second opinion from a shop with the right diagnostic tools made all the difference. For anyone facing similar symptoms, definitely have the pressure sensor connections checked before assuming the worst.