VW T-Roc Power Loss & Limp Mode: ECU Fault Alert

Had a similar situation with my 2014 VW Golf GTI. The sudden power loss and engine performance issues matched exactly what you describe. After proper diagnostics, the main relay turned out to be defective, causing intermittent ECU communication problems. The repair involved replacing the main power relay unit and performing a complete system reset. The issue was serious since the faulty relay affected multiple control system functions, including fuel management and throttle response. The automotive electronics were essentially getting incorrect power supply, leading to those performance drops. This kind of problem often gets misdiagnosed as ECU failure, which would be much more severe. The relay replacement fixed all symptoms, and the car has been running perfectly for the past 18 months. Would recommend getting the relay tested specifically, as its failure symptoms closely match your description. Key diagnostic signs were: Unusual power loss while driving, Engine performance fluctuations, ECU error codes related to power supply, Inconsistent electronic system behavior Make sure the shop specifically checks the main relay before exploring more complex ECU repair options.

Thanks for sharing your experience with the GTI relay issue. In my T-Roc I had exactly those symptoms, and the car diagnostics also pointed to similar control system problems. After your post I had my mechanic check the relay first, and you were right, it was indeed the culprit. Would you mind sharing how much you paid for the complete repair? I am curious if repair costs have increased since your fix. Also, have you experienced any other automotive electronics issues since the relay replacement?

After seeing your mechanic about the ECU problems in your T-Roc, I am glad to hear they found and fixed the faulty relay. The repair cost for my main relay replacement was 120€, including parts and labor for the computer module reset. Sounds like vehicle electronics prices have stayed fairly stable since my repair. Have not experienced any car diagnostics issues or ECU-related problems since the fix. The engine control unit has been working flawlessly, with no power losses or performance issues. The key was getting the correct diagnosis early, many shops jump straight to assuming major ECU repair is needed when it can often be a simpler relay problem. The stable performance after the fix confirms that focusing on the relay first was the right approach. These control system issues can be tricky to diagnose, but once properly fixed, they typically stay resolved.

I took my T-Roc to my regular mechanic yesterday after reading about the relay issue. The symptoms matched exactly, unusual power loss, fluctuating engine performance, and error codes from the vehicle electronics. The mechanic confirmed the faulty relay diagnosis after testing the control system. Total repair cost came to 150€, which included the new relay unit and a full computer module reset. A bit more than what you paid, but still way better than a complete ECU repair. The car now runs perfectly with no engine performance issues. Really glad I asked here first, saved me from unnecessary expensive repairs since some shops were suggesting full ECU replacement. The automotive electronics are all working normally again, and the error codes have cleared completely.