VW Crafter ECU Issues Causing Power Loss Problems

Having experienced similar issues with a T6 diesel (2019 model), I can share some relevant insights about vehicle electronics and ECU problems. The symptoms you describe match what I encountered, reduced power and ECU error codes. After running several car diagnostics tests, my workshop identified a defective main relay affecting the computer module functionality. The repair process was straightforward: Complete diagnostic scan, Main relay replacement, ECU reset, Test drive to confirm fix Total cost was 120€ including parts and labor. The repair restored full engine performance and cleared all error codes. Before suggesting specific solutions, could you share: Build year of your Crafter, Current mileage, Specific error codes stored in ECU, Any recent repairs or maintenance, Additional symptoms besides reduced power This information would help determine if your issue matches what I experienced or if further diagnostics might be needed.

Thanks for sharing your experience. My Crafter's last service was just 2 months ago at 84000KM. After reading your reply, I checked the control system again and got error code P0401 (EGR Flow). The automotive electronics diagnostic also highlighted low voltage to the EGR valve, which seems connected to the power reduction issue. The main relay suggestion is interesting, would that explain why the ECU problems started immediately after a cold start? I'd rather try the relay replacement first before considering a complete ECU repair since the cost difference seems significant. Do you know if relay testing can be done without removing the component?

Based on your error code P0401 and the EGR flow issue, I had a similar situation with my T6. The electrical connection to the EGR valve can definitely trigger reduced power mode through the control system. In my case, the cold start correlation was identical. The engine performance would drop right after startup, which initially pointed to the main relay. However, after further testing, it turned out the EGR valve connector had corroded, causing inconsistent voltage readings in the automotive electronics. The fix involved: Cleaning the EGR valve connector, Replacing the wiring harness section, Computer module reset, Test drive verification Total repair cost was 180€, significantly less than ECU replacement. For relay testing, yes, it can be done while installed using a multimeter to check voltage drops. However, the EGR-related error code suggests focusing diagnostic efforts on the EGR system first rather than the relay. Given the low mileage and recent service, I recommend having the workshop check the EGR valve connections before exploring more complex vehicle electronics repairs.

Thanks for the detailed responses. I've scheduled a workshop visit for next week to check both the EGR system and relay. The system reset and EGR cleaning suggestion makes sense given my error codes and cold start symptoms. The cost estimate helps set realistic expectations too, much better than a full ECU replacement. Will report back on what the diagnostic testing reveals about the engine performance issues. From what you've shared, it seems the control system problems are likely connection-related rather than a failed ECU. Hopefully cleaning the EGR valve connections and checking the vehicle electronics will resolve the reduced power mode. The detailed repair steps provided will help me discuss the issue more knowledgeably with the technician. Really appreciate the specific troubleshooting guidance and cost insights shared here.