"""Yes, In a book that tells you how the system works."
I'm sure the Wayne found thet usefull ""

Are you for real Glen?

What do you expect from a post asking for so much, yet providing so little?

The DTC definition provides a direction in which the diagnostic process should follow, yet the poster has provided no evidence of relevant testing or any other testing come to that.

"Customer have changed boost postion control valve and pressure sensor"....

So this looks like an unqualified repairer has referred the job to someone with a "Snappy" who has access to the "Holy Grail" that is UKAT!

No disrespect intended Wayne, but in future, you really should provide something to display some input on your part (other than an investment in a scan tool)

Sorry Glen, but useful feedback has to be earned!