VW T5 Fuel System Issues Causing Engine to Stall

I had a very similar issue with my VW Transporter 2.0 TSI from 2015. Having some experience with fuel system problems, the symptoms you describe sound familiar. Initially, I also suspected fuel contamination, but after taking it to the workshop, they found that a loose connector at the fuel pump was causing irregular fuel mixture in the combustion chamber. The symptoms matched exactly, rough idle, power loss, and engine warning light. The diagnostic showed the fuel pump wasnt getting consistent power due to a damaged wiring connection. The repair involved fixing the connector and cleaning the surrounding area to prevent future corrosion. Total cost was 95€ including diagnostic and repair. To properly assist, could you share: Have you checked the fuel consumption lately? When was your last fuel filter change? Are you getting any specific error codes? Did these issues start after refueling at a new station? Consider checking your fuel filter first, as clogged filters can cause similar symptoms. Also, fuel additives might help if theres water in your fuel system, but lets first determine the exact cause before suggesting solutions.

Last service was 2 months ago at 50397km. After reading through responses, I checked the fuel consumption and noticed it increased by about 15%. The error codes point to P0171 (System Too Lean) and P0300 (Unusual Misfire). The engine knock became more noticeable after filling up at an unfamiliar station. I tried using premium fuel additives to clean potential contamination, but the symptoms persist. The fuel filter was changed during the last service, ruling that out as a cause. The workshop experience shared about the fuel pump connector issue is particularly interesting since my symptoms match. Will have this checked specifically when taking it in. The gradual onset of problems does align with a deteriorating electrical connection rather than sudden fuel contamination.

Thanks for the additional details. The P0171 and P0300 codes combined with increased fuel consumption strongly suggest a fuel delivery issue, very similar to what I experienced with my Transporter. In my case, the deteriorating connector also initially presented with a lean condition code before developing into misfires. The 15% consumption increase you mentioned matches the pattern, my fuel economy also worsened as the fuel pump struggled to maintain proper pressure. The fact that premium fuel additives didnt resolve your issue further supports the electrical theory over fuel contamination. When my connector was faulty, additives made absolutely no difference because the root cause was the inconsistent power supply to the fuel pump. A few observations based on what happened with my VW: The lean condition eventually triggered unusual misfires, Symptoms worsened gradually over weeks, Engine knock increased with engine load, Premium fuel made no noticeable improvement Since your fuel filter is new and symptoms persist despite additives, I strongly recommend having the fuel pump electrical connections inspected. The repair should be straightforward if its the same issue I encountered. The diagnostic time was minimal since they knew where to look, keeping costs reasonable.

Based on your feedback and repair experiences shared, I'm now pretty certain the fuel pump electrical connection needs inspection. My symptoms align perfectly with your case, especially the gradual onset and the fact that premium fuel additives made no difference. The matching error codes (P0171 and P0300) plus the similar 15% increase in fuel consumption really points toward the same fuel delivery issue you experienced. Looking back, the problems did develop slowly over time rather than suddenly after refueling, which makes more sense with an electrical issue than fuel contamination. Your insight about the fuel pump connector causing irregular fuel mixture explains why my engine runs particularly rough during warm-up. Since my fuel filter is new and fuel system cleaners havent helped, I feel more confident now about what to tell the workshop to check first. Good to know the diagnostic and repair costs were reasonable in your case. I will have them specifically check the fuel pump connections when I take it in next week. The whole fuel system seems affected, but at least now I have a clearer direction for the diagnosis.