I have a 2010 Volkswagen Golf and was told by a garage that the high pressure fuel pump had disintegrated and blocked the injectors. I was later told by a main Volkswagen dealership that I had mis-fueled the vehicle with petrol. I knew that I had never filled this diesel vehicle with petrol and employed a chartered mechanical engineer to sample and test the fuel. The fuel was sent to a specialist lab and they found that the fuel was perfect and free from all contaminants and no metal swarf was in the fuel oil. I was told by the engineer to take the vehicle to a diesel specialist.

They found that the fuel pump was in perfect working order but that all four injectors were not working correctly. As there was no issue with the fuel and that the injectors were not damaged by metal particle and that the high pressure fuel pump was and still is in perfect working order could you provide me with an explanation as to why all four injectors could fail at the same time.