I have a 2007 1.9 TDI Golf. A month ago it wasn't sounding very happy so it went into the garage (independent VW specialist) where it was diagnosed as being a faulty injector (number 4). Injector was changed. When it was collected we were told they also had to change the injector harness. Anyway, it all ran fine.
A month later, same problem again. Engine is only running on three cylinders, sounds and runs just as it did before. Had the AA out and he confirmed its an injector fault (AA recovered it, I caught the train, it turned up at the house covered in mud with the rear light cluster smashed so god knows what happened there
I suspect the first time around they changed the injector and it still didn't work, hence they changed the harness. But on that basis it's unlikely to be the harness again as its had a new one.
Does anyone else have any ideas? I'm going to whip the rocker cover off tomorrow and try and establish which injector is playing up. I have a funny feeling its going to be number four again. Going to swap that over with another and see if its the injector or the power supply to the injector. Does the injector feed straight back to the ECU? Really hope its not an electrical issue as this is going to be tricky!