How much Def?
Posting Guru
Joined: Aug 2007
Posts: 1,902
Likes: 26
From: BA, OK
Depends on the year I believe. I've heard the 17+ trucks have a larger DEF tank than the 11-16 trucks?
On average DEF is consumed at 1 gallon per 1000 miles. Using that average with a 5 gallon tank and doing the math it had 1/2 gallon of DEF left and would take 4-1/2 gallons to fill up. Some people like waiting for the 200 to empty message. This will also allow you to fit 2 boxes of DEF into the truck without any waste. Myself I fill it up after I see it has dropped below 1/2 full and when I'm at a pump with DEF.
On average DEF is consumed at 1 gallon per 1000 miles. Using that average with a 5 gallon tank and doing the math it had 1/2 gallon of DEF left and would take 4-1/2 gallons to fill up. Some people like waiting for the 200 to empty message. This will also allow you to fit 2 boxes of DEF into the truck without any waste. Myself I fill it up after I see it has dropped below 1/2 full and when I'm at a pump with DEF.
Fleet Mechanic
Joined: Jan 2016
Posts: 1,804
Likes: 113
You could stop at a truck stop and just fill it. I do it on every fourth or fifth tank. I think the most I have added at the pump is 2 gallons.
Edit to add. Generally the DEF at truck stops at the pump is 1/3 of having to buy a 2.5 gallon jug.
Edit to add. Generally the DEF at truck stops at the pump is 1/3 of having to buy a 2.5 gallon jug.
Post Fiend
Joined: Nov 2001
Posts: 6,748
Likes: 119
From: Tallassee, ALabama
If you are going to fill from a jug, stop by your local Ford Parts Dept and get the Ford DEF nozzle. You can usually buy it for less than $7. P/N PM-27-N. It fits snug and prevents over filling the tank and getting DEF spills. DEF will damage the paint over time. You can wash it out and reuse it.
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Cargo Master
Joined: Mar 2008
Posts: 2,975
Likes: 19
From: Archdale,N.C.
Sorry guys, it's a '14 Lariat. Thanks for the info .Yeah I checked a while back and it showed half, this week the 500 miles to empty popped up. I haven't really tracked the mileage. Yeah its a bit of a drive but I may just drive to a truck stop for the pump Def.
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Cargo Master
Joined: Mar 2008
Posts: 2,975
Likes: 19
From: Archdale,N.C.
OK I went to a truck stop and filled it with Def. The message was 434 miles to empty and it took 4.45 gallons to fill it. Just wanted to update for future searches. Thanks guys.
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Cargo Master
Joined: Mar 2008
Posts: 2,975
Likes: 19
From: Archdale,N.C.
OK... Backstory with another question.
Ive been getting the P20b(I think ) for the reductant heater. Of course my Vin doesn't fall under the service bulletin. A while back I got the message Def level was at half. This week I got the message of 500 miles to empty. I normally just clear the reductant heater code using Forscan. Sometimes it will stay off for a day sometimes it will come back on at the next restart.
Now.. The miles to empty had gotten down to 445 and I had a cel. No problem, I'll just clear it as always. But..This time it's a P21ab code for the Def level sensor.
Is it normal for the cel to come on simply due to needing to add Def? Is it possible for the level sensor to slowly die as the heater is dieing and its just showing? If I replace the heater does the level sensors come with the heater replacement kit? Sorry for the long questions but I've only had this truck since August and I'm still learning. If it's not clear what I'm asking just ask the right questions back and we'll go from there haha. Thanks
Edit : The Def level in the message center changed from miles to empty to Def level OK immediately after restart.
Ive been getting the P20b(I think ) for the reductant heater. Of course my Vin doesn't fall under the service bulletin. A while back I got the message Def level was at half. This week I got the message of 500 miles to empty. I normally just clear the reductant heater code using Forscan. Sometimes it will stay off for a day sometimes it will come back on at the next restart.
Now.. The miles to empty had gotten down to 445 and I had a cel. No problem, I'll just clear it as always. But..This time it's a P21ab code for the Def level sensor.
Is it normal for the cel to come on simply due to needing to add Def? Is it possible for the level sensor to slowly die as the heater is dieing and its just showing? If I replace the heater does the level sensors come with the heater replacement kit? Sorry for the long questions but I've only had this truck since August and I'm still learning. If it's not clear what I'm asking just ask the right questions back and we'll go from there haha. Thanks
Edit : The Def level in the message center changed from miles to empty to Def level OK immediately after restart.
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Posting Guru
Joined: Aug 2007
Posts: 1,902
Likes: 26
From: BA, OK
There is also a doorman aftermarket unit that is much cheaper than the one listed above.
I didn't look up what those codes are but it is common for the DEF level sensors to do wonky things at times and will usually correct itself in a few miles or key cycles.
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Jan 23, 2008 02:43 PM