Our 2012 ford f150 has started dropping miles. The screen that shows miles left to drive according to the gas in the tank. The gas mileage (currently 17.3) has stayed the same. But we can drive 40 miles and the miles drop by 100 and we use a ton of gas. There are no leaks anywhere and the truck sounds like it’s running fine. What the heck is going on? I am definitely not a mechanic. Please help.

 

Welcome to the site!

Suggest the miles-to-empty is viewed by many as a guess rather than the real deal.

If your driving habits have changed recently, another degree of difficulty with its estimations based on past history.

Then, there's the summer/winter fuel blend transitions going on now, or amounts of ethanol allowed / used. Missouri has an ethanol mandate of 10%, soon going to 15%, but an out where if ethanol per gallon costs more than straight regular per gallon, don't have to put it in. When fuel was cheap a couple years ago, OBD scanner was reading 0% ethanol.

On the off chance you've switched between regular fuel and E85 - E85 likely will deliver only about 3/4 of the mpg as regular.

Suggest to start tracking actual mileage manually - fuel put in to the same level, assumed to be the Full level clickoff at the pump against the actual miles travelled.

Sure, there could be something else going on, but if the vehicle is otherwise running fine with nothing else unusual noticed, suggest verifying the internal calculation as a first step.

 

it is called the “lie o meter” for a reason.

 

Has your engine temperature changed? Colder engine uses more fuel so monitor your engine temperature gage. If engine is running to cold, change thermostat.

 

lol...you are NOT "using a ton of gas", your consumption (MPG) hasn't suddenly increased by several factors. Do not even remotely assume that 'miles to empty' means ANYTHING. It can be and IS affected by dozens of factors.

 

The system estimated MPG is 1 - 1.5 MPG more than reality for my truck, from my observations of calculating my mileage at every fill up.