VW Tiguan Diesel No-Start: Electrical System Failure

Had similar issues with a 2011 VW Passat TDI. The symptoms match what you describe, engine failing to start and error codes related to the ignition circuit. The root cause turned out to be a failing relay switch in the starter circuit combined with corroded connections in the wiring harness. The voltage drop was significant enough to prevent proper starter engagement. Main repair steps involved: Testing the power supply to the starter solenoid, Replacing the main starter relay switch, Cleaning all ground connections, Inspecting the entire wiring harness for damage, Checking fuse box connections This was a serious electrical issue that required specialized diagnostic equipment. The complete failure to start is typical when multiple electrical components are affected. The corroded wiring harness was actually causing intermittent voltage issues across several systems. Would strongly recommend finding a shop with experience in VW electrical diagnostics. These symptoms typically dont resolve themselves and can lead to additional component failures if left unchecked. The fact your mechanic didnt resolve it suggests they might have missed checking the complete ignition circuit path including the relay switch and wiring harness connections.

Thanks for sharing that detailed response about the electrical issues. I actually faced something very similar with my 2009 Tiguan last winter, the car would not start and kept throwing electrical system codes. Turned out it was a combination of corroded battery terminals and a failing relay switch that was causing the problems. The mechanic did a thorough check of the wiring harness and found several spots where the insulation had worn away. Did you end up getting it all sorted out? Would be helpful to know the final repair cost in your case, as prices for electrical work seem to vary quite a bit. Also curious if youve had any other electrical gremlins pop up since the repair? Sometimes these issues can signal the start of other electrical problems in the fuse box area.

Happy to report the electrical issues were completely resolved. After bringing it back to the shop, they identified and fixed the Terminal 15 ignition positive interruption that was causing the starting problems. The total repair cost came to 95€ for fixing a faulty cable connection in the ignition circuit. Since the repair, the voltage drop issues disappeared and the car starts perfectly every time. The key was finding a technician who properly diagnosed the complete ignition circuit path. The wiring harness and relay switch are working as intended now, with no additional electrical problems showing up. A proper diagnosis makes all the difference with these electrical gremlins. When the right connections are repaired, these systems are actually quite reliable. No issues with the fuse box or other electrical components have emerged in the months since the fix.

Thanks for the follow up. I finally got my car fixed last week. After checking multiple shops, I found a specialist who immediately spotted the issue. The car would not start due to a damaged starter solenoid and some badly corroded battery terminals. The total repair came to 280€, more than your case but still reasonable considering they replaced the entire starter assembly and cleaned up all power supply connections. The mechanic also checked the complete wiring harness while the car was in, which gave me peace of mind. Car starts perfectly now, no more error codes showing up. Really glad I took the time to find the right shop instead of throwing more money at the first mechanic who clearly missed the real problem. Having a proper diagnostic check of the electrical system made all the difference.