DEF gauge

the_jeepeo

Member
Joined
Mar 3, 2021
Messages
12
Reaction score
10
Location
CA
Vehicle(s)
Rubicon
Approaching 2k miles on the new EcoDiesel and the DEF gauge hasn't moved from 100% full.

With the 10k mile theoretical full tank range, shouldn't I see at least 10 to 20% movement on that gauge?

I saw elsewhere that we shouldn't expect the DEF gauge to be "precise" or "accurate".

Any other input on this output issue?





Advertisement

 

grimmjeeper

Well-Known Member
Joined
May 6, 2021
Messages
80
Reaction score
106
Location
Castle Rock, CO
Website
www.grimmjeeper.com
Vehicle(s)
1987 Comanche, 2001 Cherokee, 1997 F250
The sending units on tanks of all kinds aren't great when you get towards 100% full or 100% empty. There was probably DEF fluid in the filler neck that you're using up. Until that's gone, the tanks will stay "full".

Same thing that happens with a fuel tank. Fill it up to the very top where fuel is at the cap and you will run for many miles before the gauge starts to come down.
 

GearWhore

Well-Known Member
Joined
Dec 10, 2018
Messages
281
Reaction score
272
Location
Utah
Vehicle(s)
2021 JLUR Diesel, 1972 Arctic Cat Climber, 2006 Triumph Speed Triple
Build Thread
Link
Occupation
Gentleman Explorer

40”JLURD

Well-Known Member
First Name
Ross
Joined
Aug 20, 2020
Messages
646
Reaction score
483
Location
Southern California
Vehicle(s)
2021 JL Unlimited Rubicon Diesel
Occupation
Bad Mother Fucker
Approaching 2k miles on the new EcoDiesel and the DEF gauge hasn't moved from 100% full.

With the 10k mile theoretical full tank range, shouldn't I see at least 10 to 20% movement on that gauge?

I saw elsewhere that we shouldn't expect the DEF gauge to be "precise" or "accurate".

Any other input on this output issue?
That’s crazy I already had put in 2.5gal of DEF by 2,000 miles...
 

SteveSRT

Member
First Name
Steve
Joined
Dec 12, 2020
Messages
23
Reaction score
16
Location
Sparks, NV
Vehicle(s)
GMC Denali, 2nd Gen Ford Raptor and Wrangler 392 (on order)
Most DEF tanks don't have your standard float sensors like fuel tanks. Instead they will have 3 or 4 parts that will estimate what's left in the tank. They aren't all that accurate especially on the fuller end. As someone else said it should be around 3% of your fuel consumption so people getting better MPG will use a lot less.
 

gregssstaaa

Member
First Name
Greg
Joined
Aug 19, 2020
Messages
19
Reaction score
55
Location
San Diego
Vehicle(s)
2020 Jeep Wrangler Unlimited Willys EcoDiesel
Vehicle Showcase
1
My DEF didn't move from 100-99% until about 300 miles in.
I'm at about 4300 miles now and a little less than 50%.
 

AZ-Chris

Well-Known Member
First Name
Chris
Joined
Mar 24, 2020
Messages
134
Reaction score
133
Location
Arizona
Vehicle(s)
2020 JL Unlimited Rubicon Diesel
I'm quite pleased with my overall fuel efficiency. I have 8K miles since I took delivery and my recent road trip from Phoenix to Las Vegas and back netted an average of 29 mpg. However, my DEF usage is higher than I expected . . . I've added more than three, 2.5 gallon jugs of DEF myself and my DEF tank was full when I took delivery.
 

Gorilla57

Well-Known Member
Joined
Jan 3, 2019
Messages
398
Reaction score
468
Location
Chandler AZ
Vehicle(s)
2019 JLUR Mojito
I'm quite pleased with my overall fuel efficiency. I have 8K miles since I took delivery and my recent road trip from Phoenix to Las Vegas and back netted an average of 29 mpg. However, my DEF usage is higher than I expected . . . I've added more than three, 2.5 gallon jugs of DEF myself and my DEF tank was full when I took delivery.
Just doing a rough calculation on your approx fuel use over 8k miles (guessing 23-24mpg) which puts you at 340-ish gallons of fuel. Multiply that by 3% and that nets you 10.2 gal of DEF. That usage puts you right where you should be for DEF.
 

AZ-Chris

Well-Known Member
First Name
Chris
Joined
Mar 24, 2020
Messages
134
Reaction score
133
Location
Arizona
Vehicle(s)
2020 JL Unlimited Rubicon Diesel
Your math isn't working for me. My fuel efficiency has never dropped below 26 mpg per fill-up (hand calculated) and typically sits in the 27 mpg range. I have used more than 12.5 gallons of DEF since taking delivery, and odometer is sitting 8,350 mi.

Please correct me if I'm wrong, but I thought Jeep stated that 10 gallons of DEF were needed for every 10K miles. If I am incorrect, what was Jeep's stated DEF usage rate?
 

Gorilla57

Well-Known Member
Joined
Jan 3, 2019
Messages
398
Reaction score
468
Location
Chandler AZ
Vehicle(s)
2019 JLUR Mojito
Your math isn't working for me. My fuel efficiency has never dropped below 26 mpg per fill-up (hand calculated) and typically sits in the 27 mpg range. I have used more than 12.5 gallons of DEF since taking delivery, and odometer is sitting 8,350 mi.

Please correct me if I'm wrong, but I thought Jeep stated that 10 gallons of DEF were needed for every 10K miles. If I am incorrect, what was Jeep's stated DEF usage rate?
No reason to say “your math isn’t working for me”. I was just going off of what you had said “more than three, 2.5 gal jugs”. You never gave exact numbers of: DEF use, actual miles on the Jeep, average fuel economy.

As for Jeep saying 10k miles for 10gal of DEF, that would mean average fuel usage of 30mpg as DEF is consumed at a 3% rate.

You seem to be averaging a very high mpg, so that’s great. But, if you can prove to Jeep that you are using significantly more DEF than you should, then they need to look into why.
 

AZ-Chris

Well-Known Member
First Name
Chris
Joined
Mar 24, 2020
Messages
134
Reaction score
133
Location
Arizona
Vehicle(s)
2020 JL Unlimited Rubicon Diesel
I apologize if I've offended you, it certainly wasn't my intention.

In my previous post, I indicated that I've added 3 jugs of DEF (typically 2.5 gallons per jug) and that my tank was filled at delivery (5 gallons). I also stated that I had more than 8K miles.

Also, I've never seen any documentation that states a DEF consumption rate of 3% of fuel consumption rate, though I do recall Jeep claiming a one tank of DEF per 10K miles. Given what I've read from Jeep and others on this forum, there is a clear discrepancy on DEF consumption expectations. Why Jeep set an unrealistic expectation is beyond my comprehension.

My ultimate position is that I don't really care what my DEF consumption rate is, as long as I experience trouble free operation. DEF is not liquid gold and it's not difficult to monitor and add when needed (I just add a jug whenever the DEF tank reads approx 25% full). However, I hope a higher DEF consumption rate is not a harbinger of bad news down the road. DEF expense is inconsequential too me, particularly since diesel is frequently 5 to 10 cents less per gallon than regular unleaded in my area.
 

Gorilla57

Well-Known Member
Joined
Jan 3, 2019
Messages
398
Reaction score
468
Location
Chandler AZ
Vehicle(s)
2019 JLUR Mojito
I apologize if I've offended you, it certainly wasn't my intention.

In my previous post, I indicated that I've added 3 jugs of DEF (typically 2.5 gallons per jug) and that my tank was filled at delivery (5 gallons). I also stated that I had more than 8K miles.

Also, I've never seen any documentation that states a DEF consumption rate of 3% of fuel consumption rate, though I do recall Jeep claiming a one tank of DEF per 10K miles. Given what I've read from Jeep and others on this forum, there is a clear discrepancy on DEF consumption expectations. Why Jeep set an unrealistic expectation is beyond my comprehension.

My ultimate position is that I don't really care what my DEF consumption rate is, as long as I experience trouble free operation. DEF is not liquid gold and it's not difficult to monitor and add when needed (I just add a jug whenever the DEF tank reads approx 25% full). However, I hope a higher DEF consumption rate is not a harbinger of bad news down the road. DEF expense is inconsequential too me, particularly since diesel is frequently 5 to 10 cents less per gallon than regular unleaded in my area.
I did a search on DEF usage a long time ago, before buying my 2015 Ram 3500 diesel and I found back then 1.5-3% DEF to fuel consumption. Lately, most things say 3%.

http://blueskydefna.com/importance-calculating-def-consumption/

http://hollonoil.com/DEF/def_usage.htm


https://www.cumminsfiltration.com/sites/default/files/MB10033.pdf

As for getting 10k miles out of 5.5 gal of DEF, Jeep was WAY off. There’s no way with the current consumption rate. My wife’s diesel Touareg would go 10k miles on 5gal of DEF and we all know how well that turned out. :headbang:
 

AZ-Chris

Well-Known Member
First Name
Chris
Joined
Mar 24, 2020
Messages
134
Reaction score
133
Location
Arizona
Vehicle(s)
2020 JL Unlimited Rubicon Diesel
Interesting links above. Thank you for providing these links.

The last link seems to indicate that my higher than expected DEF usage rate may be contributing to my seemingly above average fuel efficiency numbers . . .
 

Gorilla57

Well-Known Member
Joined
Jan 3, 2019
Messages
398
Reaction score
468
Location
Chandler AZ
Vehicle(s)
2019 JLUR Mojito
Interesting links above. Thank you for providing these links.

The last link seems to indicate that my higher than expected DEF usage rate may be contributing to my seemingly above average fuel efficiency numbers . . .
I'd rather burn a little more DEF and less fuel. Just means you are running that lean....which is a good thing...:like:
 

Advertisement




Stinger Off-Road
 



Advertisement
Top