Hi Alan, thanks for the reply. I had a chance to look at the vehicle again yesterday. It is something that I had not considered. I didnt expect a filter to block up so fast. Looking at the sensor readings, key on engine off, 0mb proving the sensor plausibility, start and idle around 300mb, which I think is high, then under load goes up to 600mb and as high as 1000mb at times. I think your right, the filter is starting to block up again already, and considering the vehicle had the ability to block the old one solid to cause the non start in the first place this seems likely. I've checked and cleaned the EGR which was stuck closed, replace the air filter which was very dirty. I carried out a leak off test on the injectors which shows around 70% difference between the highest and lowest reading with the others all in between. I have suggested to the customer that the next course of action may be to test and recondition or replace the injectors. He wasn't very keen on this idea given the cost and no guaranteed fix. I'm not sure of how to prove the fault any further with testing alone. Thank you for your time, Kind regards, Andy