Tiguan Diesel Power Loss Linked to ECU Malfunction

I experienced nearly identical symptoms with my 2014 Touareg TDI. The engine performance dropped noticeably and the control system started showing irregular behavior. Initially, I was skeptical about ECU problems being the root cause. The diagnostic revealed multiple error codes in the engine control unit. After thorough testing, the main relay was confirmed defective, causing intermittent power supply issues to the automotive electronics. This affected various computer module functions, leading to reduced engine performance. The repair involved replacing the main relay and recalibrating the ECU. While this was a serious issue that could have led to complete system failure if left unaddressed, the fix itself was straightforward once properly diagnosed. The symptoms completely disappeared after the repair. Key indicators that pointed to electronic control issues rather than mechanical problems: Inconsistent power delivery, Multiple system warning lights, Engine performance fluctuations, Normal mechanical sounds despite power loss Given your similar symptoms and vehicle age, having the ECU thoroughly checked is a sensible first step. These control system issues typically dont resolve themselves and can worsen over time.

Thanks for sharing your experience with the ECU repair. Since we have such similar issues, I will check the main relay first. Feeling more confident now about the car diagnostics route my mechanic suggested. Quick follow up, do you remember the total cost for fixing the engine control unit issues? Also, has everything been running smoothly since the repair? I want to make sure I budget correctly and know what to expect long term with these vehicle electronics.

Following up from my previous post, I can confirm everything has been running perfectly since the repair completed. The car diagnostics were spot on and fixing the main relay resolved all the performance issues. The total cost came to 120€ for the complete repair, which included replacing the defective relay and recalibrating the engine control unit. The vehicle electronics have shown no problems since the fix, and the engine performance returned to normal immediately. The automotive electronics in these models are generally reliable once properly repaired. Six months later, the control system continues working flawlessly with no recurring issues. Looking back, I was initially worried about a much more expensive repair, but addressing the faulty relay early prevented any additional damage to the ECU. Definitely worth getting it fixed promptly when these symptoms appear.

Thanks for the helpful responses. I went ahead and had my mechanic check the main relay and ECU system. Turns out you were right, it was indeed an electrical issue affecting the engine control unit. The repair cost was 180€ total, a bit more than expected but still reasonable considering it fixed the power issues completely. The mechanics found some corroded connections in the control system that were causing intermittent problems with the computer module. After replacing the damaged components and performing a system reset, the car is running like new again. The performance is back to normal and all warning lights have cleared. Really glad I followed through with the ECU diagnostics rather than assuming it was a major mechanical problem. For anyone else experiencing similar symptoms, definitely worth having the vehicle electronics checked early before the issues get worse. Thanks again for steering me in the right direction with this repair.