Dpf cleaned and mileage dropped 1 mpg

[Trucker750]

(05-08-2018 )Rawze Wrote:  There are a lot of causes for fuel mileage dropping. Simply cleaning the DPF properly is not one of them. Something else caused it. Perhaps they worked on something else or replaced a sensor with a defective one?. Maybe a leaky doser injector?

They swear up and down they didnt touch anything else except the dpf filter. I know it has been a fleet truck belonging to them since new, and while they have always kept good maintained I'm pretty sure they have never cleaned any of the egr or intake system. I'm planning to clean it all, but I dont want to until I'm sure that is the sole cause of the mileage loss. Is it possible that a clogged intake system could account for the instant drop of 1 mpg just because the dpf was cleaned? Maybe the egr valve is so clogged it can't open normally, and the change is exhaust backpressure is now requiring more or less flow that the clogs will allow, equaling lost mpg? All without throwing codes? I'm a mechanic as well as a driver, but the computer systems nowadays are new to me.