Diagnose Hi Pressure fuel pump failure


New member
Jul 21, 2021
Hello everyone I have a problem with my 1.6tdi caddy 2011 changed injector as I have done twice before and coded it but the van would not start never had a problem with the same job before ? VCDS shows not enough fuel pressure in the rail , I have vacumed fuel through the hi pressure pump from the pump return and it comes through but never clears all the bubbles , so I isolated just the hi pressure pump no tank or filter, fuel fom container to pump inlet and vacume on pump outlet but still get bubbles air so it must be the pump letting in air somewhere ? is that an indication it is bad ? The annoying thing is the car drove fine before changing the injector so how could the pump go bad ? it was sitting for around 3 months before getting round to sort it due to covid . Any suggestions please, any help gratfully received , thank you.


Staff member
Apr 22, 2006
Nottingham, England
That sounds like the HPFP ran dry and ate itself, this throws metal particles into the system which blocks the injectors. After working on this system you must use VCDS to bleed the circuit using the lift pump.