VW Touran Won't Start, Immobilizer System Alert

Having dealt with similar immobilizer fault issues on my VW Golf 2006, I can relate to this starting problem. The symptoms you describe match what I experienced, the anti-theft system was preventing the engine from running properly. After some basic troubleshooting, my workshop identified that the key programming was incorrect, causing communication issues between the key and the ignition control module. The fix involved reprogramming the transponder chip in the key, which cost 45€ and resolved the problem completely. Before jumping to conclusions though, could you share: Have you noticed any other electrical issues recently? Does this happen with both keys if you have a spare? Are there any specific error codes stored? Has any recent work been done on the electrical system? The immobilizer system on these VW models can be sensitive, but its worth confirming its not something simpler. Sometimes the issue can be related to the key transponder, other times its the immobilizer control unit itself. Based on your description, it sounds very similar to an immobilizer fault, but having these additional details would help narrow down the exact cause and suggest the most effective solution.

Just had the annual service done last week, so Im quite frustrated with this new issue. After reading your response, I checked with my spare key and got exactly the same behavior, engine tries to start then dies immediately. Error codes point to P1573 (Engine Control Module Communication Error with Immobilizer). No other electrical problems noted before this started. The car electronics seem otherwise normal, including power windows and radio. Given both keys show identical symptoms, Im starting to think its the immobilizer control unit rather than a key issue. Ive heard the control unit replacement can cost around 300€. Anyone know if theres a way to confirm this before committing to such an expensive repair?

Thanks for providing those additional details. After seeing that both keys show identical symptoms and the specific P1573 error code, it definitely strengthens the case for an immobilizer control unit fault rather than key programming issues. When my VW developed similar symptoms, I initially hoped it was just the key signal causing problems, but the diagnostic ultimately revealed a faulty immobilizer control module. The security light behavior and immediate engine stalling matched your description exactly. The repair cost was around 280€ for the control unit plus programming. Some shops suggested an immobilizer bypass solution which was cheaper, but I opted for the proper fix to maintain the security features. The replacement resolved all starting issues and cleared the P1573 code permanently. Before you proceed with the repair, have the shop verify: The wiring connections to the immobilizer unit are secure, The key reader coil around the ignition switch is functioning, No water damage is present in the control module area These checks should be included in the diagnostic fee and will confirm whether a full unit replacement is truly needed. Given the age of these VW models, immobilizer control unit failure is a known issue, especially after recent work that might have disturbed the electrical systems.

Thanks for that detailed feedback. The error code P1573 and matching symptoms with both keys really helps clarify things. After hearing about your similar experience with the immobilizer control unit, I feel more confident about the repair direction. Will definitely get those wiring and key reader coil checks done first. Good point about potential disturbance from the recent service, maybe something got knocked loose. Though given the clear error code and classic symptoms, Im preparing for the control unit replacement cost. Based on your experience, 280€ for a new immobilizer control unit plus programming seems like the going rate. While not cheap, its better to fix it properly than risk issues with a bypass solution. At least the car electronics and key signal are working normally otherwise. Will book it in next week and make sure they do those preliminary checks you suggested. Thanks for sharing your repair costs and experience, really helpful to know what to expect with these VW immobilizer system issues.