# Low Fuel Range Innaccuracy?



## bales9er (Oct 15, 2019)

Anyone else notice a fairly significant difference between what the range tells you when the fuel light comes on and how many gallons you actually fuel up with? On our extended test drive of an SEL the fuel light came on and said 45 mi left, we literally drove it 10 miles and it went down to 15 miles left. We put 2 gallons in figuring that was more than enough to get us back to the dealership which was another 10 miles and when we pulled in there it said 5 miles left. Fast forward to our own Atlas now and my wife just had a 35 mi range (im guessing 2 gallons left based on mpg) and she filled up with 14 gallons. With an 18.6 gal fuel tank capacity it seems like there is at least a 2 gallon discrepancy. Seems like it makes you rush to a gas station whereas you really have another 30-40 mi to play with.


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## GTINC (Jan 28, 2005)

Why would this be an issue? Unless you live in an area without available fuel outlets why would it matter? Is there some benefit to ever letting the tank being less that 1/4 full?


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## brachiopod (Sep 15, 2018)

Yes, every recent car I've owned does this. There is a couple gallons left when it says range is zero. There are a reasons for this, but one is that it is not good for your fuel pump to run it out all the way, you could burn it out. The other is I suppose liability. You just have to factor it in if you want to run it out all the way.


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## bales9er (Oct 15, 2019)

Yeah obviously don't want to run it out of gas but itd be nice if it was a bit more accurate...it was very puzzling to see the gauge go down in front of my eyes right after I put a couple gallons in. I knew in my head I couldn't be running out of fuel but also not knowing the vehicle it was hard to not trust it. Needless to say we cut the test drive short because of it but I suppose that didn't deter us from buying one haha


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## GTINC (Jan 28, 2005)

bales9er said:


> Yeah obviously don't want to run it out of gas but itd be nice if it was a bit more accurate...it was very puzzling to see the gauge go down in front of my eyes right after I put a couple gallons in. I knew in my head I couldn't be running out of fuel but also not knowing the vehicle it was hard to not trust it. Needless to say we cut the test drive short because of it but I suppose that didn't deter us from buying one haha


What is the advantage of ever letting it get below 1/4 tank?


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## mhjett (Oct 16, 2000)

As a data point, I just filled up our 3.6 after the trip computer said 0 mile range. It took 16.833 gallons, so in theory there were about 1.8 gallons left in the tank. So to carry the theory further I could have driven about 50 more miles before the tank was completely dry. 

Moral of the story, you _could_ drive until it says 0 miles remaining, if you wanted. I tend to be safe and fill up at the latest when, or just before, the fuel light comes on.


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## GTINC (Jan 28, 2005)

mhjett said:


> As a data point, I just filled up our 3.6 after the trip computer said 0 mile range. It took 16.833 gallons, so in theory there were about 1.8 gallons left in the tank. So to carry the theory further I could have driven about 50 more miles before the tank was completely dry.
> 
> Moral of the story, you _could_ drive until it says 0 miles remaining, if you wanted. I tend to be safe and fill up at the latest when, or just before, the fuel light comes on.


Can you think of any reason to ever let the vehicle get below 1/4 tank? Do you live in an area with no access to fuel?


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## bales9er (Oct 15, 2019)

Good to know thanks for the info. i agree best to fill up way before that happens and we typically do but if you're in a pinch its good to know you don't have to scramble for a gas station if you're getting close to 0 miles on the range.


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## KarstGeo (Jan 19, 2018)

If you enable the "gallons to fill" with OBDEleven/VCDS it's really easy to deal with all of this and it's very accurate. You know it's an ~18.5 gal tank and you see 16 to fill, well you know you have 2.5 left @ whatever your mpgs are for miles you can go. Simple.


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## Tim K (Jan 31, 2001)

I was playing with OBD11 today and there's an item under dashboard called "defuel threshold". It is set to 9L. That's about 2.3 gallons. I bet this is what triggers the low fuel warning. I'm guessing you could set this lower if you'd like it to be more accurate.


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## Mrprice (Jul 30, 2013)

Anyone try modifying the “defuel” setting? Just about every fill up with 0 range remaining, I’m putting in about 14.8 gallons. It’s crazy that there should be almost 4 gallons left in the tank.


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## KarstGeo (Jan 19, 2018)

Mrprice said:


> Anyone try modifying the “defuel” setting? Just about every fill up with 0 range remaining, I’m putting in about 14.8 gallons. It’s crazy that there should be almost 4 gallons left in the tank.


I've never taken mine to 0 range but a fill with the light on is typically 16 gal for me. I will have to mess with that setting.


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## GTINC (Jan 28, 2005)

Mrprice said:


> Anyone try modifying the “defuel” setting? Just about every fill up with 0 range remaining, I’m putting in about 14.8 gallons. It’s crazy that there should be almost 4 gallons left in the tank.


Why is this an issue? No filling stations where you live?


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## Icantdrive65 (Nov 8, 2001)

My friend rented a Dodge Caravan to drive to Arizona. He was running low on a long stretch of highway somewhere in the middle of nowhere. The van ran out of gas on him while the range said he had 15 miles to empty.


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## Mrprice (Jul 30, 2013)

Anyone mind sharing where to enable “gallons to fill?”. I have VCDS but was hoping to save some time. Also, anyone have any follow up regarding the “defuel”? Did it help?


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## KarstGeo (Jan 19, 2018)

Mrprice said:


> Anyone mind sharing where to enable “gallons to fill?”. I have VCDS but was hoping to save some time. Also, anyone have any follow up regarding the “defuel”? Did it help?


https://r.tapatalk.com/shareLink/to...hare_fid=1056328&share_type=t&link_source=app

Sent from my SM-G973U using Tapatalk


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