My Signum was chucking a loada smoke out from the engine compartment last night BUT no warning lights on the dash and running sweet as a nut. My mate who owns a garage is taking a look at it later but from what i've described to him he reckons it could well be the EGR valve, apparently a common fault on Signums and Vectras. Big job is it and what sort of expense am i looking at IF its the EGR valve? Anyone any ideas please? Thanks.