Last week we had this Citroen Dispatch dropped off by a local garage for us to read the faults and log some data. Once we moved the vehicle into the workshop we read the fault codes and found P0299 underboost. This normally relates to a boost leak, EGR or MAP sensor fault. We also noticed that the DPF filter was near the maximum loading so we performed a static DPF regeneration. The customer had been advised by a local diesel specialist to change all 4 injectors prior to a visit to his local garage and subsequently to us. We advised all 4 injectors would be highly unlikely after the diagnostic test results we had read.
We advised the garage of our findings and they carried out further investigation. The cure in this particular case was to replace or disable the EGR valve as the EGR plunger had become detached from the EGR valve itself.