LZO mileage dropped off big time.

[alliz86]

Hi everyone! - long story short, I log my fuel and have averaged 25mpg (mostly highway but it’s combined) we left on a trip through the prairies and it’s dropped to 19mpg for two tanks now.  No headwind, flat prairie roads.  I don’t have any engine codes, but have the BlueDriver ob2 reader.  All my dpf pressures aren’t reading anything and the exhaust temps weren’t reading.  We got to our destination the truck stayed and cooled off over night, I am getting pressure readings and exhaust temps again with BlueDriver, but the mileage is still ******.  Any recommendations? Maybe DC the battery for awhile and see what happens after it kind of resets? 
thanks for any input. 

[slimjim2525]

Try changing the fuel filter.  My MPG dropped noticeably, changed the fuel filter and came right back to its normal.

[redwngr]

Do both coolant reservoirs still have the correct amount of coolant?

 

Any evidence that there might be a leak between of 'boost air'  between the turbo and the intake? 

 

DIC has pages for fuel filter and air filter condition.

Might have to be 'turned on' in the settings menu to be able to see them