Have a couple of 2007 Volvo 780's, question is, what part of the egr valves fail? Do they fill with soot, do they overheat? Do the electronics fail? Can a guy remove them and clean them if they're acting up, or if they're registering codes is it already too late?speeking of codes, anyone aware of anyplace a guy can get a list of volvo fault codes? Spent 240K and the dealer won't give it up? Would be nice when these occor on the road, in the middle of the night, to be able to know what system is being problematic.