VW Transporter Power Loss: Tips from Real Owners

I had a very similar issue with my 2014 VW Caddy, which shares many components with the Transporter. As someone with moderate experience in car maintenance, I knew right away this was beyond basic DIY fixes when multiple fault codes appeared on my scan tool. The dashboard light and sudden power loss you describe matches exactly what happened to me. My vehicle went into limp mode after getting custom chip tuning from a non-authorized tuning shop. The vehicle diagnostics revealed that the engine control unit was compromised by incompatible software modifications. The workshop had to reset the engine control unit to factory settings and properly recalibrate all systems. Total cost was 180€ for diagnostics, reset, and testing. Since then, no issues with performance or error codes. Before suggesting more specific solutions, could you share: Which engine variant your Transporter has? When was the last time any engine modifications were done? What specific fault codes is your car computer showing? Has there been any recent maintenance or repairs? This information would help determine if your issue is similar to what I experienced or if it might be something else entirely.

Last service was just 2 weeks ago at 48159km. What intrigues me is that your case sounds exactly like mine. My diagnostic scan tool also showed multiple fault codes after the power loss. The engine control unit reset you mentioned makes sense since I recently had aftermarket performance software installed. Before taking it to the dealer, I will try disconnecting the battery for 30 minutes to see if the car computer resets itself. If the dashboard light persists, I will have the ECU checked professionally. Can you recommend the best way to document all the fault codes for the workshop? I want to make sure they have complete information about what the car computer is reporting when I bring it in.

Thanks for those additional details. Since I went through nearly the same situation, I can definitely help regarding the fault codes documentation. When my engine issue appeared after the aftermarket tuning, I used my scan tool to save a complete diagnostic report. Most modern scan tools have a save or export function, this gives the workshop the full history of fault codes, not just the current ones. A key tip from my experience: Take screenshots or photos of your scan tool display showing the fault codes. The workshop will particularly want to see any codes related to the engine control unit. In my case, the car diagnostic report helped them quickly identify the software conflict causing the reduced engine power. I should mention that while the battery disconnect trick sometimes works for basic issues, it likely wont resolve ECU problems caused by incompatible tuning. My attempt at this same reset method didnt clear the dashboard light or restore full power. Given your similar situation with aftermarket software, I strongly recommend having a professional workshop properly reset and recalibrate the ECU. The risk of causing further complications through DIY fixes isnt worth it when dealing with engine management systems.

Thank you for pointing me toward checking the ECU first. You were right about the battery reset, I tried it but the dashboard light came right back on when I started the engine. I've documented all the fault codes from my auto scanner as suggested, including taking photos of each diagnostic code displayed. I called the workshop and booked the Transporter in for tomorrow morning. They mentioned they see a lot of ECU-related issues with aftermarket tuning, so they should be able to diagnose and fix it quickly. The car diagnostic data I collected will help them verify if its the same software conflict you experienced. Will post an update once the workshop determines if a full ECU reset and recalibration resolves the reduced power issue. Really appreciate your detailed responses and sharing your similar experience, saved me from trying other fixes that likely wouldnt have helped.