puddles

Greetings all
Has anyone seen this fault or could offer some help?
Car was flying down the motorway until I slowed down to turn on to a side road. The glow plug light started to flash and car went in to limp mode. Managed to get to a friends house where I parked up for the night. Tried to start the next day, light still flashing with just the ignition on. Took a while to start, lots of white smoke and sod all power. Managed to limp to a garage (white smoke stopped once driving) and had fault code P2339 diagnosed. Told it was cylinder 4 fault but trying to get head around fault being present when engine not running...! Have replace knock sensor but fault still wont clear. Various things on web saying it could be all sorts of issues from cam sensor to crank sensor. Injectors may need recoding but dont believe it is the injectors as they were all replaced last year. I have also replaced fuel filter and checked for debris. Gut feeling is electrical but I am no mechanic so any help would be welcome!!
Many thanks

oldford

P2339 - Cylinder 4 Above Knock Threshold
That's usually means new injector(s).

packman

Arr that also means £££££££

puddles

Injectors only replaced last year - would like to think they would last longer?? The fault will clear but pops straight back again with the engine not running as soon as you read the DTC's.
Would the fault light still come on with the ignition before I even try to start the car? If the engine is not running, how does it know an injector is shot? I need to learn more about the inner workings of the car and the ECU pre-start checks. Are there any "red herrings" that can generate this fault code?
Thanks for the replies..