Crafter's Multiple System Failures Point to Power Issues

I had a very similar issue with my 2015 VW Transporter diesel last year. As someone with moderate experience working on VW commercial vehicles, these symptoms immediately reminded me of what I went through. The multiple warning lights, system failures and unusual control module issues turned out to be caused by a faulty cable connection to the main control unit. The scan tool was showing various error codes that kept changing, just like in your case. The intermittent nature of the problem made it particularly tricky to diagnose. After some back and forth with my workshop, they traced it to corroded wiring in the BUS system connection. The check engine light flickering was a key indicator that pointed to an electrical connection issue rather than individual system failures. The repair involved replacing and properly sealing the cable connections to the control module. Total cost was 155€ and it completely resolved all the unusual system failures and warning lights. Before suggesting this might be the exact same issue though, could you share: Have you noticed any correlation with weather conditions? Does it happen more when the engine is cold or warm? Which specific error codes is your scan tool showing? Are there any signs of water ingress around the main wiring loom? This information would help confirm if your issue matches what I experienced with my Transporter.

Latest service was at 189000KM and all warning signals disappeared for a while after that. Looking at the responses, the corroded wiring suggestion makes sense. After running another scan tool diagnostic yesterday, I noticed the malfunction indicator appears more frequently when driving through wet conditions. The main control module seems particularly affected on cold starts. The service required warning also started appearing out of nowhere last week. Error codes keep changing but consistently show communication faults between different control modules. Will check the wiring loom connections as suggested since water exposure seems to trigger more system failures. Has anyone specifically checked if theres a technical service bulletin related to this wiring issue for 2017 Crafters?

Thanks for the update on your Crafter situation. Your symptoms exactly match what I experienced with my Transporter, especially the correlation with wet conditions and cold starts triggering more warnings. After dealing with my case, I learned that moisture ingress around the main wiring connections is a known weak point. The warning light behavior and changing error codes during system failure are classic signs of corroded BUS system wiring. The OBD-II scanner showing communication faults between modules further confirms this pattern. My shop mentioned they had seen several similar cases where water exposure gradually degraded the connections. The temporary improvement after your service makes sense, they likely cleaned some connections while working on other items. Since you mentioned checking for technical bulletins, while getting my repair done, I found there was actually a service campaign for sealing and protecting specific wiring harness points. Worth having your workshop verify if your VIN is covered. The repair in my case involved: Complete inspection of all main harness connection points, Replacement of corroded terminals, Application of dielectric grease, Installation of additional water protection covers Total repair time was about 4 hours and the engine diagnostics have shown no communication errors since then. All system failures and warning lights have remained resolved for over 8 months now.

Given what everyone shared, I believe I have a good handle on my Crafter issue now. The evidence points strongly to water-affected wiring being the culprit. The warning signals getting worse in wet conditions and the correlation with cold starts matches the experiences shared. I scheduled an appointment with my workshop to inspect the main wiring connections and BUS system. Asked them specifically to check for corrosion and water ingress, since the scan tool keeps showing those communication faults between modules. The check engine light behavior definitely suggests an electrical rather than mechanical issue. Will have them verify any service bulletins for the 2017 model year. The suggested repair process involving new terminals, dielectric grease and additional water protection makes sense. 155€ seems reasonable if it fully resolves these unusual system failures. Thanks for the detailed feedback. Will update once the workshop completes their diagnosis with the OBD-II scanner and confirms if corroded wiring is indeed causing all these control module issues.