VW Tiguan Electrical Gremlins, Multiple System Failures

As someone with moderate experience working on VWs, I had a very similar issue with my 2015 VW Golf with the same symptoms. The check engine light and various system warnings would appear out of nowhere, and the control module would act up, especially affecting electronics. After trying basic troubleshooting, I took it to a workshop where they ran detailed OBD-II diagnostics. The root cause turned out to be a faulty cable connection to the main control unit that manages the BUS system communications. These intermittent electrical issues are frustrating because they can trigger multiple fault codes without showing a clear pattern. The repair involved replacing damaged wiring and ensuring proper connections to the control module. Total cost was 155€, and it completely resolved the unusual system failures and warning lights. To better assist with your specific case, could you share: Have you noticed any correlation between these issues and weather conditions? Which specific warning lights appear most frequently? Does the problem occur more often when the engine is cold or warm? Has the service required light been consistently on or does it also come and go? This information would help determine if your Tiguan is experiencing the same underlying issue or if there might be a different root cause.

Thanks for the detailed information about similar electrical issues. My Tiguan last had its service 4 months ago at 116000km. The warning lights appear more frequently during cold starts and wet conditions. Most common alerts are system failure notifications on the dash, along with check engine warnings that reset after turning the car off and on. The service required indicator stays off, but engine diagnostics show multiple temporary error codes. The weather correlation is interesting, when driving in rain the infotainment glitches happen more often. Did your repair also fix issues with the entertainment system, or was that a separate fix?

Thanks for those additional details. Yes, the wiring repair on my Golf actually resolved both the system warnings and entertainment system glitches. The water sensitivity you describe strongly points to the same electrical connection issue I experienced. The correlation between wet conditions and system failures is a classic sign of compromised wiring. In my case, the engine diagnostics showed similar unusual error codes that would clear after a restart. When moisture got into the damaged cable housing, it would disrupt the BUS system communication, triggering multiple warning signals and system failures. A few tips based on my experience: Get the wiring checked specifically around the main control module, Have the mechanic inspect the cable insulation and connection points, Request a thorough OBD-II scan during both dry and wet conditions The entertainment system issues are typically part of the same problem since they run through the same communication network. Once the faulty wiring was fixed on my Golf, all the sporadic electronics problems, including the audio and navigation cutouts, stopped completely. The fact that your issues increase during cold starts also matches my experience, as temperature changes can affect compromised electrical connections. This combined with the moisture sensitivity makes a strong case for checking the wiring integrity around your control modules.

Thanks for confirming that the entertainment system issues were related to the same wiring problem. That helps narrow down my search. Based on your experience, I will have my mechanic focus on inspecting the wiring and connections, especially around the main control module. The system failures happening more during wet conditions and cold starts really does match what you described. Makes sense that compromised wiring could cause all these unusual malfunction indicators and error codes. I will schedule an appointment to have them do a full diagnostic scan and wiring inspection. Hopefully they can trace the issue to damaged cables like in your case. The 155€ repair cost would be worth it to resolve all these intermittent control module issues. Good to know this is likely fixable without major component replacement. I was worried the unusual check engine warnings meant something more serious. Will update once I get the wiring checked out and repairs completed.