"DEF low, but you know it's not" problem

BenK wrote:
Reason asking is that am thinking DEF is sensitive to light...

Optical, some, shine a light into the bottle via a special plastic lens that
has an angled cut

That angle has the light bounce enough back if not submerged to tell the
computer the level is below that lens

If submerged, then the angled cut will NOT bounce back light, but pass it
through into the bottle

Wondering if that light degrades the DEF

Floats have their problems too...

Ben, I'm not exactly sure to be truthful with you...The gauge in the truck is non linear and not very good....it'll stay on full for quite a while...I just topped off...showed I had a quarter of a tank and I put 4.5 gallons in, (tank holds 5.5 gallons)....I understand if level get's too low you will get a message telling you that you need to refill within "X" amount of miles.

Booklet states the DEF injection system consists of the following components:
DEF tank
DEF pump
DEF injector
Electronically-heated DEF lines
DEF control module
NOx sensors
NH3 sensor
temperature sensors
SCR catalyst.

It seems like the intensity of Direct sunlight is not good for the DEF, wouldn't think a light sensor , if that is what were to be used, could cause a break down like direct sunlight would.

I've had this truck 2yrs, 2 months and have 32,100 miles on it at this time....Have never had an issue with DEF, compariing this truck to my 10' and 12'....this truck, though heavier, get's better MPG than the other two. Never had an issue of even coming close to putting DEF in diesel fuel filler neck, nor putting diesel in DEF filler neck, (pump, small or large wouldn't be able to fit into the DEF filler neck...

I purchase my DEF at the pump...I have a truck stop about 5 miles from the house and fill up there....at $2.79 a gallon, it's cheaper than the 2.5 gallon cartons you can buy. Though, if I were to go on a long trip, I might buy one of these containers to be "better safe than sorry"...