Recently I have encountered a pretty significant decrease in fuel economy with my LBZ. Unloaded in warmer weather, I was averaging ~20mpg and getting ~650 miles out of a 34 gallon tank. My last tank, the 'feed me' light came on with only about 490 miles on the tank (~14mpg). No current DTC's, no abnormal noises, it still runs great. I did throw a code in November (fuel pressure related) and the truck limped for about a mile before I got it home and changed out the fuel filter. After installing the new filter, I reset the DTC and the decreased fuel economy seems to have followed... but it's been pretty cold since the filter change as well.

Is it likely the recent cold weather we've had is the culprit? Winter blend fuel? I recall a bit of a decrease in fuel economy last winter but don't remember it being so much. I do have the grille cover installed.

For what it's worth, I seem to notice a slight decrease in engine power since the filter change in November. I had been running WIX 33910 fuel filters but changed to a Baldwin BF7827 this time around.