VW Fox Diesel Cold Start Issue: Bad Injector Alert

I experienced something very similar with my 2008 VW Polo diesel. Based on my intermediate level experience working on diesel engines, those cold start problems matched my symptoms exactly. The rough idle and starting issues were classic signs of a faulty fuel delivery system. After running an injector test at my regular workshop, they confirmed one of the fuel injectors was defective. The irregular fuel injection pattern was causing those cold start problems, especially during low temperatures. The repair involved replacing the problematic injector and recalibrating the fuel system, which cost me 515€ in total. Since the fix, cold starts have been smooth and the engine runs perfectly even in cold weather. The fuel delivery is now consistent and the rough idle completely disappeared. To better assist with your situation, could you share: Current mileage on your Fox, Check engine light status, Any diagnostic codes pulled, How long have you noticed these symptoms, Any recent fuel system maintenance These details would help determine if your Fox is facing the same fuel injection issues I encountered with my Polo.

Thanks for sharing those details about the injector replacement. My Fox has 25821km on the odometer since my last service. You make a good point about the fuel delivery system, the symptoms do sound identical. I will get the injector test done to confirm if this is causing my hard starting troubles in the cold. Did your workshop mention anything specific about injector cleaning as a possible solution before going for a full replacement?

I hear you about exploring injector cleaning before replacement. With my Polo, I actually tried that route first. The workshop did attempt a professional fuel injector cleaning service for 150€, but it only provided temporary improvement to the engine misfire and cold start issues. After about 2 weeks, the same symptoms returned, rough idle during cold starts and inconsistent fuel delivery. The injector test they ran after the cleaning showed the injector was mechanically worn, which no amount of cleaning could fix. That is when we proceeded with the full replacement I mentioned earlier. Given your Fox has similar symptoms and runs on the same fuel system design, I would recommend going straight for the injector test. While injector cleaning might seem like a cost-effective first step, if your injector is mechanically compromised like mine was, you will end up paying for both services. The workshop can quickly determine through proper diagnostic testing whether cleaning might help or if replacement is necessary. This prevents wasting money on intermediate solutions when the core issue is a worn injector.

Thanks everyone for the input on the cold start troubles. Based on what I have learned, I will take my Fox in for a proper injector test first thing next week. Not going to waste time with cleaning since the fuel injection symptoms match exactly what was described, especially that rough idle during cold starts. My regular workshop does fuel system diagnostics, so I will let them check the entire fuel rail setup while they are at it. Hopefully the fix is as straightforward as a single injector replacement. Will update once I know more about what is causing these cold start issues. The 515€ cost reference is helpful for budgeting too, so I appreciate that detail. For now, I will just have to deal with the hard starts and rough running until the test confirms exactly what is wrong with the fuel delivery.