DEF message

Still running DEF (Yea, I know).....anyway

I get the message that I have DEF for 500 miles. So I get a 2.5 gallon jug to refill as I'm going on a 850 mile tow. I begin to fill the tank and prior to getting all the 2.5 gallons in, the tank overflows and spill DEF all over the place...WTF!!! :biggun:

Is one of the sensors bad?

Also, I added the Exhaust Filter Capacity message through IDS. When I'm driving, sometimes I get the "Cleaning Exhaust Filter" message and other times I don't. When I'm driving, I scroll through the dash and look at the Exhaust Filter fullness. This previous time, I saw the "Exhaust Filter Full" message and was expecting the "Cleaning Exahust Filter" message but didn't get one. I scroll through the filter screen a few minutes later and saw that the filter was 40% full.....WTF!!!:biggun:

Billy T.
[email protected]

I never add DEF until I get the message that it's less then half. Last time it didn't take the whole 2.5 gal either. My cleaning exhaust filter message seems to depend on how I'm driving it. On the highway it never comes on.


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tom.boswell.79 said:

I never add DEF until I get the message that it's less then half. Last time it didn't take the whole 2.5 gal either. My cleaning exhaust filter message seems to depend on how I'm driving it. On the highway it never comes on.


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Less than 500 miles should mean about 4.5 gallons.

OP, was the tank actually full, or did you dump it in too fast that is couldn't vent the air fast enough.

I figured it was low as previous times when I got the 500 mile message. But yes, it was flowing in like it was empty then all of a sudden it overflowed. I pulled out the fill tube and tried it again, overflowed again. Tried it three times and all resulted with an overflow.

Billy T.
[email protected]

I've noticed with mine that it takes a few cycles for the message to go from '500 miles' or 'less than 1/2 full' back to 'Level OK' after a refill. Mine rarely takes a full box even at the '500 miles message'

I might have a sensor you may have if that helps

The fill neck on these can be finicky. Motorcraft has a reusable spout that clicks on to the fill neck to prevent any spilling, as well as a vent tube in it to get as much DEF in there as possible, if you're not already using it. It's the only way I've been able to get mine completely full without making a mess.