VW Tiguan Power Loss & Rough Running: Fix Guide

Having some experience with VW diesels, I faced nearly identical symptoms with my 2018 VW Golf TDI. The check engine light came on, accompanied by power loss and inconsistent acceleration. After initial diagnosis, the problem was traced to a faulty fuel injector. The air-fuel ratio was completely off, causing the engine to run poorly. The workshop performed a thorough diagnostic test which showed one injector was not delivering fuel correctly. The repair involved: Complete diagnostic scan, Removal and testing of all fuel injectors, Replacement of one defective injector, System reprogramming, Test drive to confirm fix Total cost was 515€ including parts and labor. The repair resolved all symptoms, no more jerking, proper power delivery, and the check engine light cleared. Before suggesting specific solutions for your case, could you share: Current mileage, Any recent maintenance performed, Whether you notice any unusual exhaust smoke, If the fuel consumption has changed, Whether the problem is constant or intermittent This information would help determine if your Tiguan is experiencing the same fuel injection system issue or if its related to other components like the oxygen sensor or catalytic converter.

Thanks for sharing that experience. I had my last service at 135000km and am now at 137706km. After reading your response, I checked my service records and noticed the mass air flow sensor was already flagged for attention during my last inspection but wasnt replaced at the time. The symptoms match what you described with your Golf TDI. The jerking during acceleration seems worse in cold weather. My local mechanic initially suspected the oxygen sensor but given the similarity to your case, I will have them check the fuel injectors as well. I do notice grey smoke occasionally from the exhaust now, which I didnt mention in my first post. This combined with the poor acceleration really points toward a fuel delivery issue rather than just a sensor problem. Would you recommend getting the intake manifold checked while they are diagnosing the injectors? Since theyll need to access that area anyway, it might make sense to inspect everything while its opened up.

Thanks for those additional details. The grey smoke combined with the cold weather performance issues definitely reinforces my initial suspicion about the fuel injection system. Having gone through this with my Golf TDI, these symptoms are textbook signs of injection problems. The mass air flow sensor being flagged previously is significant, its interaction with the fuel injectors directly affects the air-fuel mixture. When I had my injector replaced, the shop also found carbon buildup in the intake manifold, which was contributing to the problems. Getting the intake manifold checked while they are in there is absolutely worth it. During my repair, the technician explained that the intake manifold inspection only added about 30€ to the diagnostic cost since the components were already accessible. The carbon cleaning service for the intake manifold ended up being necessary and cost an additional 180€, but prevented future issues. Based on your mileage and symptoms, I would recommend: 1. Full fuel injector diagnostic 2. Intake manifold inspection and cleaning 3. Mass air flow sensor replacement 4. Verification of oxygen sensor readings My total repair costs including the intake manifold service came to around 750€, but preventing further damage to the catalytic converter made it worthwhile. The combination of grey exhaust smoke and cold weather performance issues is very similar to what I experienced before the repair.

Based on that useful information, I will definitely have my mechanic do a complete check of both the injectors and intake manifold. The combination of symptoms you experienced matches my situation exactly, especially the grey smoke and cold weather performance issues. I just booked an appointment for next week and mentioned both the fuel injectors and intake manifold inspection. The shop quoted roughly 800€ for a complete diagnostic and likely repairs, which aligns with what you paid. They also agreed its smart to check the mass air flow sensor since it was previously flagged. Dealing with the check engine light and power loss has been frustrating, but hearing about your successful repair gives me confidence that these symptoms can be fully resolved. Will make sure they verify the oxygen sensor readings as well, since everything seems connected to achieving the proper air-fuel ratio. Really appreciate you sharing the detailed breakdown of your repair experience. Having a clear idea of the potential costs and repair scope helps set realistic expectations. Will update once I get the final diagnosis and repair completed.