I have a 64 plate 1.6 tdi and the engine management light has been on since I bought the car in Feb 2019. The error code comes up as dpf but I have had it done countless times and the light still come back on. On my last attempt at Halfords, they said the engine rumble/ vibrates at 4k revs. Anyone knows what could be the issue. It drives perfect and pulls like there is no issue