I bought a used 04 D/A a while back and noticed the fuel mileage guages are way off - almost 2x reality. I never have been concerned but what could be causing this (perf flash, sending unit etc.)?

Is the truck tuned? If so, that'll throw it all off.

Mine has always been off , 2 mpg better than reality . It always takes more fuel than it says was used . If you find a cure let us know.

Seems these trucks are all different. Mine has been within a .1-.5 everytime I check it. After tuning it it actually was better than the DIC claimed. I think its a crap shoot as to whether or not these things even work form truck to truck.

Pretty sure i'ts been tuned. Since I bought it, I have driven a few others both tuned and not - es it has been tuned. wasn't sure if that's what would cause the mpg to bee that far off - almost two times, not two mpg

thanks