Thanks again, The p0400 fault code occurs intermittently whilst driving & it has occurred a few times when just revving up in workshop. I have read about cutting feedback wire, but thought is was bull.i am waiting for customer to bring vehicle back to me to spend a little move time on it.Check to see what software version, etc.my tech 2 does'nt go back to 2004 so unable to see sub code.no No smoke test yet, I was really thrown with fault code relating to feedback, live data showing feedback incorrect on 2 scan tools & voltage on pin 4 being 4.5 volts without changing.going on diesel Bosch course in 2 weeks will be interested in hearing what mark Carter says about this feedback signal & what it means. Many thanks.