VW Eos Won't Start: Faulty Ignition Switch Alert

Had the same symptoms on a 2011 VW Golf GTI with the 2.0T engine. The problem turned out to be more than just a basic ignition switch issue. After running diagnostics, the main culprit was a corroded battery terminal connection that caused voltage drop across the entire starting circuit. The voltage inconsistency was triggering multiple error codes and preventing proper communication between the ignition switch and the starter relay switch. The fix required cleaning both battery terminals, replacing the main positive cable running to the fuse box, and updating the immobilizer system. This was classified as a serious electrical issue since it affected multiple systems. The degraded connection could have eventually led to ECU damage if left unaddressed. The repair shop had to remove several components to access and replace the damaged wiring harness sections. Recommend getting a proper diagnostic test focusing on voltage readings at different points in the ignition circuit. A reputable shop should be able to pinpoint if its a simple connection issue or something more complex in the ignition switch pathway. It sounds very similar to what happened with my car, the initial symptoms point to the same root cause in the electrical system.

Thanks for sharing that fix. Mine started working after they repaired it but I am curious about a few things. Did any other electrical gremlins pop up after the repair was done? Also wondering what kind of repair costs you ended up with since my power supply issues seem pretty similar to what you described. The starter solenoid and ignition switch repairs can get pricey so it would help to know what to expect. My mechanic mentioned the voltage drop issue could come back if they dont fix all the corrosion points.

Just got the car back from the shop two days ago. The Terminal 15 ignition positive circuit repair cleared up all the starting problems completely. Final bill came to 95€ for fixing the faulty wiring connection, much cheaper than replacing the entire ignition switch or starter solenoid. No other electrical issues have shown up since the repair. The voltage drop readings are now stable across all test points in the power supply circuit. The mechanic did a thorough cleaning of all battery terminals and connection points to prevent future corrosion problems. This kind of electrical fix is actually pretty straightforward once they properly diagnose the specific circuit that's causing trouble. The key is having them test the complete ignition switch pathway rather than just throwing parts at it. The starting sequence works perfectly now, no more error codes or hesitation. Just make sure they document the repair properly in case anything similar pops up down the road.

Thanks everyone for the insights. I just got back from the mechanic after they completed the repairs. After thorough testing, they found corroded connections in my wiring harness causing the voltage drop issues, just like others mentioned. The total repair came to 280€, which included cleaning all battery terminals and replacing some damaged wiring sections near the fuse box. The car starts perfectly now and all error codes are cleared. My mechanic showed me the old corroded parts and explained how the poor connections were interrupting power to the ignition system. Much better than my previous experience where they just kept replacing expensive parts without fixing the root cause. Will keep monitoring to make sure the car wont start issues dont return, but so far everything is working as it should. Really glad I asked here first, saved me from another potentially costly misdiagnosis at a different shop.