VW Jetta Diesel: Diagnosing Fuel Filter Heater Issues

Had nearly identical issues with my 2004 VW Passat TDI. These symptoms definitely sound familiar, and having some experience with diesel engines helped identify the problem. The fuel filter heater connection was indeed faulty, causing intermittent fuel delivery issues. Initially thought it was just a clogged fuel filter causing poor fuel efficiency, but the workshop diagnosed a damaged wire connection to the heater element. The constant engine stalling and rough idle were major red flags pointing to fuel delivery problems. Got it fixed at a workshop, total cost was 95€ for diagnosis and repair of the cable connection. The repair involved replacing the damaged wiring and ensuring proper connectivity to the fuel filter heater assembly. After the fix, fuel efficiency returned to normal and the engine stalling completely stopped. What transmission type does your Jetta have? Also, can you share the specific error codes? This would help confirm if your issue matches what I experienced. These details would be useful to determine if youre dealing with the exact same fuel line problem or if there might be additional concerns to address. Would also recommend having them check the entire fuel filter assembly while theyre at it. Sometimes these issues can be related to a filter replacement thats overdue.

Thanks for the detailed response. Just checked my service records, last filter replacement was at 82000km. The transmission is manual 5-speed. Getting these specific error codes from the scan tool: P0180, Fuel Temperature Sensor A Circuit P1201, Fuel Filter Heater Circuit Low The symptoms match exactly what you described. Good point about checking the full fuel filter assembly. Given the age of these diesel engine components and my mileage being at 86047km now, might be worth doing a complete fuel system inspection while fixing the heater issue.

After seeing your error codes, Im even more convinced we had the same issue. My Passat showed identical codes before the repair. The fuel temperature sensor circuit error often appears alongside the heater circuit problem because theyre interconnected in the fuel system. Since your diesel engine mileage is close to when I had my issues, a complete fuel system inspection makes perfect sense. In my case, the workshop found that the wiring degradation was causing inconsistent readings from the fuel temperature sensor, leading to poor fuel efficiency and power loss. Worth mentioning that after my initial repair, I had them perform a full fuel system cleaning service. This additional step really helped restore optimal performance and completely eliminated the uneven idling that was driving me crazy. Your manual transmission setup is the same as mine, which is good news since automatic transmissions can sometimes mask fuel delivery issues and make diagnosis trickier. The clear error codes and matching symptoms suggest youre dealing with the exact same fuel line problem I encountered. Given the service interval, combining the heater repair with a new fuel filter installation would be a smart preventive measure. This comprehensive approach should resolve both your power loss and fuel consumption concerns.

Thanks everyone for the insights. After taking my Jetta to the workshop yesterday, they confirmed what was discussed here. The wiring to the fuel filter heater was indeed damaged, showing signs of wear exactly where you described. They performed a complete fuel system inspection and found that while the heater wiring was the main culprit, the fuel filter itself was also due for replacement. Had them do both repairs, replacing the damaged wiring harness and installing a new fuel filter. Total cost came to 180€ for parts and labor. The rough idle and power loss issues are now completely resolved. Fuel consumption has returned to normal levels and the engine runs smoothly again. The error codes have cleared and haven't returned. Really glad I caught this before it potentially caused more serious fuel system problems. Think I'll set up a reminder to check the fuel filter more regularly going forward, since it seems these heater issues often coincide with filter replacement intervals. Thanks again for helping diagnose this, saved me from unnecessarily replacing other components.