VW Tiguan Fuel System Issues, Rough Running Guide

Had a similar issue with my 2013 VW Golf, and your symptoms sound very familiar. With some experience working on VWs, I can share what happened in my case. The rough idle and misfiring turned out to be caused by a loose connection at the fuel pressure sensor plug. The check engine light was constantly illuminated, and the fuel economy was terrible. The fuel system was getting incorrect readings, causing the fuel injectors to deliver inconsistent amounts of fuel. Took it to my regular workshop, and they diagnosed it pretty quickly. The fix involved securing the connection properly and replacing a damaged wire in the harness. Total cost was 95€ including diagnostic time. After the repair, the engine ran smoothly again and the fuel economy returned to normal. However, to properly diagnose your specific issue, could you share: Current mileage on your Tiguan, When was the last fuel system service done, Are there any other warning lights besides the check engine light, Does the problem get worse when the engine is hot or cold These details would help determine if your issue is similar to what I experienced or if it might be something else in the fuel delivery system.

Thanks for sharing your experience. My Tiguan has 49716km and its last major service was done 3 months ago. The fuel pump and pressure sensor were actually checked during that service, everything tested fine back then. The engine misfire started about 2 weeks ago, getting progressively worse. The check engine light first appeared after a particularly rough start on a cold morning. I had the diagnostic codes read at a parts store and got P0171 which points to a lean fuel mixture. Given the recent service history, wondering if this could be related to a clogged fuel injector rather than the fuel pressure sensor. The fuel economy has dropped significantly, from around 8L/100km to nearly 11L/100km.

Based on the P0171 code and your fuel consumption increase, I am even more convinced this might not be the fuel pressure sensor after all. When I had similar symptoms on my Golf, I initially focused on the sensor too, but after getting that P0171 code, it turned out to be partially clogged fuel injectors. The rough idle and misfiring got worse over time, just like yours. I had all injectors ultrasonically cleaned and tested, cost was 280€ for the set. This resolved the lean condition and restored normal fuel economy. The check engine light disappeared after clearing the codes. A clogged injector makes perfect sense with your symptoms since: Problems started gradually, not suddenly, Fuel economy dropped significantly, Cold start issues are typical, Recent service showed good fuel pressure Before replacing parts, recommend having the fuel injectors flow-tested. Poor spray patterns from dirty injectors can definitely cause that lean condition shown by P0171. Much cheaper to clean them than replace the pressure sensor if injectors are the actual culprit.

Thanks for the detailed injector cleaning information. After reading about your experience, I scheduled an appointment with a workshop that specializes in fuel system diagnostics. They will do a complete fuel injector flow test first before looking at the pressure sensor. The symptoms match exactly what you described, engine stalling occasionally, rough idle that keeps getting worse, and the check engine light staying on. The 280€ cost for injector cleaning seems reasonable compared to sensor replacement, especially since my fuel economy has taken such a hit lately. My only concern is whether this will fix the cold start issues completely. The engine misfires are particularly bad during the first few minutes after a cold start. I will update once I get the diagnostic results and actual repair costs. Really hoping the injector cleaning resolves everything without needing additional fuel system work.