VW Jetta Hybrid Power Loss: ECU Repair Guide

I faced a similar issue with my 2012 VW Passat Hybrid, given my experience with car diagnostics and control system issues, I can share some insights. Initially, the reduced power and error codes had me worried about major ECU problems. After visiting my regular workshop, they performed a thorough diagnostic scan of the automotive electronics. The issue turned out to be a defective main relay in the computer module, rather than a complete ECU failure. The repair was straightforward once properly diagnosed, total cost was 120€ including parts and labor. Since the fix, the car has been running at full power with no recurring issues. To better assist with your situation, could you share: Have you noticed any warning lights on the dashboard? Does the reduced power occur immediately upon startup or after driving for a while? Are there any other unusual symptoms, like rough idling or stalling? Which specific error codes were shown in the diagnostics? This information would help determine if your case matches what I experienced with the main relay or if it might be a different control system issue. A proper diagnostic scan from a workshop specializing in VW hybrid systems would be the safest next step, as these symptoms can have multiple causes in the ECU system.

Thanks for sharing your experience. My latest service was done at 60000km, just a few months ago. The warning light appeared suddenly during normal driving and remained constant. The reduced power occurs right from startup. The error codes shown were P0562 and P0563, indicating system voltage problems. The engine also idles roughly when in EV mode. Your relay repair case is interesting, definitely worth checking since the symptoms appear quite similar to what I am experiencing. Might save me from a complete ECU repair if it turns out to be the same issue. Going to schedule a diagnostic scan at a workshop that specializes in system reset and ECU problems. Will update once I get a proper diagnosis of the control system.

Thanks for providing those details about the error codes and symptoms. Based on P0562 and P0563, which indicate system voltage issues, this matches even more closely with what I experienced. After tracking my repair records, the rough idle in EV mode was exactly what tipped off my mechanic to check the main relay and surrounding electrical components. The voltage-related codes are typical signs of power delivery problems to the control system, rather than a faulty ECU itself. In my case, the workshop also discovered corroded terminals at the battery connection points while diagnosing the engine performance issues. They cleaned the connections and replaced the relay as a complete solution. The total diagnostic and repair time was about 3 hours. Since your service history is recent, focus the diagnostic scan on: Main relay functionality, Battery terminal connections, Power supply to the computer module, Voltage regulator performance Given the matching error codes and symptoms, I would bet on a similar electrical supply issue rather than core ECU problems. When you visit the workshop, make sure they check these components before considering more extensive repairs.

Thanks for that detailed explanation about the electrical components and diagnostic approach. Those voltage codes P0562 and P0563 definitely point toward power supply issues rather than a complete ECU repair being needed. Makes sense about checking the relay and connections first. I have scheduled an appointment with a workshop next week that specializes in engine performance and control system diagnostics. Will ask them to specifically inspect the main relay, battery terminals, and voltage regulator as suggested. The rough idle in EV mode seems to be a key indicator, just like in your case. Really hoping it turns out to be a straightforward electrical fix like your situation rather than requiring extensive computer module work. Will make sure to get a full system reset done after any repairs. The total repair cost of 120€ in your case sounds much better than what a full ECU replacement would cost. Once I get the proper diagnosis and fix completed, I will post an update about what the actual issue was. This information could help others facing similar hybrid system problems in the future.