VW Crafter Diesel Performance Loss & Rough Running Fix

Had very similar issues with a 2012 VW Transporter TDI. The symptoms match exactly what you describe, poor performance, excessive fuel consumption and rough idle. The problem turned out to be a faulty fuel injector that was creating an overly rich mixture. A bad injector can spray too much fuel or have incorrect spray patterns, leading to uneven combustion. This affects the air-fuel ratio and triggers the check engine light. The oxygen sensor picks up these inconsistencies, which is why the engine management system shows fault codes. The repair required replacing two injectors and cleaning the fuel system. It was a serious job since contaminated fuel had caused internal damage. The catalytic converter also needed inspection as rich running can cause carbon buildup. Key signs that point to injector issues: Black smoke from exhaust, Rough idle and hesitation, Significant power loss, Higher than normal fuel consumption Worth checking the fuel filter and lines first, but given the symptoms, would recommend having the injectors tested professionally. Poor injector performance often gets worse over time and can lead to more expensive engine damage if left unchecked.

Thanks for that detailed response. My symptoms match exactly what you described. Did getting the injectors replaced solve the issue completely? Just wondering what the total repair cost was and if you had any other problems pop up afterwards. Planning to take it to a shop soon but want to be prepared for what I might be looking at cost-wise. My air-fuel ratio seems way off based on the black smoke, so definitely sounds like the same injector problem you had.

Really glad to help with an update. Yes, replacing the faulty injector completely resolved all those issues you mentioned. The intake manifold and fuel delivery are working perfectly now that the air-fuel ratio is correctly balanced. The total repair came to 515€ for diagnosing and replacing the defective injection valve. While it wasnt cheap, the improvement in performance was immediate. The black smoke disappeared, power returned to normal, and fuel consumption dropped back to expected levels. No additional problems have surfaced in the months since. The check engine light cleared and hasnt returned. Its running smoothly with no jerking or hesitation during acceleration. The mechanic also did a full system scan to ensure no other components were affected by the rich fuel mixture. Important step since running too rich can potentially damage the catalytic converter over time. If your symptoms match what I experienced, getting those injectors checked should identify the root cause. Better to address it promptly before it leads to more extensive engine problems.

Following a mechanic visit last week, I can confirm it was definitely the fuel injectors causing all those problems. The diagnostic testing showed two of them were shot, just like you experienced. The intake manifold needed a good cleaning too since all that rich running left quite a bit of carbon buildup. Total bill came to 490€, not exactly cheap but worth every cent. They had it done in about 4 hours. The difference in performance is like night and day. No more black smoke, jerking is completely gone, and the engine runs smooth as silk. Fuel consumption is back to normal too. The oxygen sensor readings are now perfect and the check engine light hasnt come back on. Mechanic showed me the old injectors, they were pretty badly worn. Good thing I got it sorted before it caused problems with the catalytic converter. Really appreciate the guidance. Helped me go into the shop knowing exactly what to expect. Would have been clueless otherwise and probably would have kept putting it off.