following on from my earlier post re. power-loss problems which I thought I had sorted, but are not........ just to recap, on my TDI 110 I'm experiencing random power loss when driving between 60-80mph and between 2500/3000 rpm - you just suddenly feel the turbo die and the car goes in to obvious limp mode but no dash warning lights are triggered. I've had a diagnostic done (not by a VAG dealer) and it showed a code referring to 'turbo overboost' - they said the most likely cause was a sticky boost pressure solenoid valve (otherwise known as an N75). Replaced this and also checked the VNT mechanism on the turbo - you could easily by hand so no problems there. After all this the problem is still there.......... so my options are replace more parts which I think it could be, and it really could be any number of things OR pay £70 for the Audi dealer to run a diagnostic program which cycles the turbo system and should point to the fault. It's been suggested it could be the EGR solenoid valve which is only £35, but then what if it isn't this either?!