Tip Buying DEF from pump

[lostinfla]

I usually buy my DEF at the pump when filling with fuel just for the convenience of not having to deal with jugs and overfilling. On our last trip, our first stop was near Ocala Fl, so I stopped before the campground to fill up. (I make it a habit to arrive at a campsite with a close to full tank). Stopped at a Loves, got fuel and DEF. While filling the DEF tank, it smelled much like an overfilled cat litter box, but I didn't think much about it. A short time after, the check engine light came on (just orange outline) with code SPN 3216/FMI 2 which translates to "Difference between the expected NOx ppm and the actual NOx ppm is greater than 200 ppm." I ended up syphoning all out of the tank and refilling with Blue Platinum from Walmart. I'm sure if we had a newer coach with the "improved" DEF head, we would have been dead in the water at that point. After running to our next camp (about 250 miles) the light went out with no ill effects. Don't assume the stuff coming out of the pump is fresh. I will NEVER buy DEF at the pump again and I'll check the date codes on the jug to make sure it's fresh.

 

[Neal]

Did you reach out to the station to report it?

Seems like there is risk either way, unfortunate we need to deal with this stuff!

 

[lostinfla]

No. It was Sunday and didn't think they would do anything anyway. You know, that would cost them $$.

 

[Joe doggs]

Back when def heads were in short supply,from Amazon I bought a device,think it’s called a refractometer….smear a little def on the lens,point to light,and it will give you the urea reading,basically tell you if the def is o.k. or not…..even today,when replacement heads are readily available might make sense to always test before filling,and if there is a vinegar/amonia smell I think that usually means the def has gone bad…….great reminder,thank you!!!

 

[Neal]

I own and carry a refractometer, never used it, probably should. I'm still on the truck stop DEF train but we've heard of stories every which way. Unfortunate we have to use this DEF stuff! I guess if we are going to be diligent, no matter the source, we should test it. Fortunately I rarely need DEF so it's not that hard for me, i.e. no excuse.

Amazon product ASIN B073Q2LSG9

 

[Underboss]

DEF is made with urea so it will smell like cat piss. I have done both and prefer truck stop DEF, its the freshest you will find. I wonder if they were getting a delivery as you were filling

 

[flyboy013]

I almost alway buy from Walmart. I test each jug with a refractometer. Never found a bad jug. I visit Walmart often enough while traveling so it’s convenient. Due to the DEF tank being located at the rear of the bus, I don’t like to fill it when fueling.

 

[Rich W.]

You're probably tired of hearing me say it but I never use pump DEF in my coach. To many reasons not to and its of no benefit to me to fill at a truck stop - it takes longer, I’d have to move the coach since the DEF fill spout is 30’ from the fuel fill, and with jugs I can fill at my leisure when stopped anyway. And since I get around 300mpg on DEF its pretty easy to plan ahead, buy enough fresh DEF for a trip and not over buy.

Also for pre-2016 emissions, which includes many 2016 coaches, it is better to keep the tank above 1/2 to keep the mechanical float wet and prevent DEF muck from crystalizing on it and making it stick causing error codes and possible derate (see the TSB below).

So I start full, drive til its down to 3/4, then fill at the next CG. It always will take 2.5 gals at that point so no waste or mess. Also I don’t buy into the “premium” DEF claims about additives, but neither do I use the cheapest stuff. And of course I verify the date codes, consider how it was stored, and if in doubt use my refractometer, which is a rare occurrence these days.

But I had two DEF related issues ending in derate shortly after I bought the coach (in my emissions rookie days) shortly after buying pump DEF. So no more. Its fine in my F250 6.7 but the Freightliner system seems to be too fragile. Or maybe its a coincidence or my imagination, but I’ve never had any issues with jug DEF.

The TSB for pre-2016 emissions: (provides the possibility of a roadside or campsite fix to avoid unnecessary shop repairs) https://static.nhtsa.gov/odi/tsbs/2013/MC-10142383-9999.pdf

I also filled in the wasted space around my DEF tank and added a dump hose box on one side and enough space for plenty of DEF on the other, and of course another compartment light and 120v outlet. Before and after shots:

OE config just screaming for better use of space.

the light was probably overkill but its what I had on hand. Also nice getting the stinky hose out of my clean wet bay.

note my refractometer handily mounted with VHB tape to the top of the tank. Now I need some gasket material to seal the door - gets dirty in there.

 

[Rich W.]

DEF is made with urea so it will smell like cat piss. I have done both and prefer truck stop DEF, its the freshest you will find. I wonder if they were getting a delivery as you were filling

It will always smell of ammonia but if its so strong it burns your nostrils to smell check it, its been exposed to too much heat for too long, the urea is breaking down, and it should be dumped. Ammonia is corrosive and damages things like the sensitive electronics in DEF headers. Not worth the risk.

 

[lostinfla]

Thanks for the idea of adding a floor to the DEF bin Rich!