MPG went up??

[palmettopowerstroke]

Usually you hear about people's MPG going down, well mine went up this week. Last week I got the "Speed limited in 50 miles. Exhaust system fault." DEF had about 500 miles left in the tank. Drove a few miles and the error message went away. When I filled up a day or so later I reset the mileage and noticed better fuel economy. Figured it would go away, but I'm almost on empty and at 14MPG. Was getting about 12.5. Same driving habits (85% city unloaded). Oddly this tank hasn't seen the highway at all. Been 100% city driving and still 14mpg. Previously I saw 16 highway and 12.5 city. I used to see about 14 city and 18-19 highway when I first got my truck, but that went away about the same time I went with off road tires. I figured the drop in MPG was the tires, but I'm not so sure now. I'm also noticing far less regens. Only 2 this tank. Before the error message it seemed like I was constantly in regen (causing the bad MPG I assume).

Anyone else experience this or can offer any wisdom? Worth taking in to see if there are any updates/re-flashes needed?

[bbc109758]

My truck always had freqent regens 75-125 and always said somthing wrong. My selling dealer charged me 128 to hook up ids and said its fine even when i said no. Months later i asked a different dealer about a different part that went bad so i could fix it myself so no surprise its normal and will cost you now pay up, but this one said let us fix your other part and check out regen problem NO Charge. Ok but there shop very busy and had for 3 long days but result was ids so good till test drive and then the readings all over the place and they found lose ground on wiring now get close to 200 miles between regen and longest 350 miles and have 30000 on ticker with half all regens in notebook. Hope that might help