HD2500 Cummins displays "Service DEF System" message intermittently

[HighDesertRam]

About two weeks ago, I received the message "Service DEF System - See dealer" on the dash intermittently, twice on one day and then several days later. I always use DEF from a very reliable high volume truck stop pump, so I believe it to be fresh. This occurred after my truck had been sitting with very little use following surgery. The first time it occurred was following a trip to the dealer for the electronic stability control software update. I never received the notice from the truck that it would be going into "limp" mode. On the three occasions where this happened the message disappeared quickly and has not happened again.

I took the truck to our local diesel specialist where I trust their knowledge and service. They threw an electronic analyzer on it (not the dedicated RAM analyzer) and saw nothing there that indicated there was a problem. I've gone another week with a couple of freeway runs and received no further error messages. However, I have a camping trip and a hunting trip coming up in September and October where I will be towing my 10,000 pound travel trailer up into the mountains (we live at 5500 feet and I will be towing to over 10,000 feet).

My OCD self has decided that I need to have the diesel shop throw the RAM specific analyzer on the truck just to ensure there is nothing further to be done.

I'd appreciate suggestions from anyone who may have experienced a similar issue or has better information than I do regarding this topic. Thank you.

 

[18CrewDually]

Get the actual codes when they scan it. It could be something as simple as a dirty DEF injector nozzle for example.

 

[Billet Bee]

How can you be so sure that truck stop def pump was reliable? The underground fuel tanks get water leakage and that same thing could of happened with the def, so I hope that was your experience since it went away fairly quickly. That's why I never personally buy def at the pump stored in a container underground, because my ocd about potential water penetration and the high expense to fix these things

 

[18CrewDually]

How can you be so sure that truck stop def pump was reliable? The underground fuel tanks get water leakage and that same thing could of happened with the def, so I hope that was your experience since it went away fairly quickly. That's why I never personally buy def at the pump stored in a container underground, because my ocd about potential water penetration and the high expense to fix these things

What he was saying was due to the high volume the DEF is sold at that location it has a high turn over rate so it more likely is fresher than a small low volume station.
Above ground tanks are less atmospheric stable since it's subjected to temperature swings resulting in wicking of moisture from the air when the fluid cools overnight. I'd rather pull from an underground tank, which have pits around the fill holes so unless the sealing cap is off during a flood it can't get contaminated.

 

[Billet Bee]

What he was saying was due to the high volume the DEF is sold at that location it has a high turn over rate so it more likely is fresher than a small low volume station.
Above ground tanks are less atmospheric stable since it's subjected to temperature swings resulting in wicking of moisture from the air when the fluid cools overnight. I'd rather pull from an underground tank, which have pits around the fill holes so unless the sealing cap is off during a flood it can't get contaminated.

Like you said, more then likely fresh, but there's no way to tell or a freshness seal or a date code. All I'm saying is poo poo happens and when my mom worked at a nationally own gas station there below ground tanks were leaking for years and taking in water and it was a known issue and nothing was done until much much later. So stuff happens and i prefer to get my def in a more controlled packaging system to keep out contaminants. Yes something could get into either scenario but in my opinion it's more likely in an underground tank situation, but thats just my ocd from seeing it happen from 2 company's I was familiar with and one of those was a commercial trucking company where they would literally throw away $20,000-$30,000 on each truck when the regen systems were failing left and right. So I had that nightmare to live with and fear which is why I'm overly cautious with our regen system, you just don't want to cut any corners what so ever when it comes to anything regen related because repair costs add up quick and never stop.

 

[Choupique]

You might ask that they drop the header from the def tank and clean it with warm distilled water, clean the injector with warm distilled water.

Something like this is usually an intermittent DEF level or quality sensor fault. It'd help to have the actual fault.

I've long stated that a standard 50k mile maintenance practice should be cleaning the def header and nozzle, and pumping some distilled water through everything. Unfortunately the latter will throw def quality faults, trigger XX miles to limp, and sometimes it's tough to make that go away. Removing and cleaning it is however generally harmless if they don't screw anything up doing it.

Filling the system with warm distilled water and pumping it all out through the injector would dramatically extend the service life of this stuff. Hot shot trucks don't really have problems with it because it stays pumping and gets consumed quickly.

 

[HighDesertRam]

How can you be so sure that truck stop def pump was reliable? The underground fuel tanks get water leakage and that same thing could of happened with the def, so I hope that was your experience since it went away fairly quickly. That's why I never personally buy def at the pump stored in a container underground, because my ocd about potential water penetration and the high expense to fix these things

You're right, I can't be 100% sure that this is the best source of DEF outside of a box with a date on it. However, this is one of the newest gas stations in town, a Mavericks, for those who live in Utah. It's less than 5 years old. Rust is not something we see much of here in Southern Utah, due to the very dry conditions we have here, so I would be very surprised if their tank was leaking.

Besides the big rigs that frequent that station (it's right next to the freeway) I might add we have a very high percentage of pick-up trucks here in this town. That station is probably frequented by many residents, too, and it's where I normally have bought my DEF since I purchased the truck in 2022.

 

[tjfdesmo]

Did the shop at leadt test the DEF with a refractometer or hydrometer?

Otherwise, I agree with flushing the DEF tank, then refill with fresh. Your initial post said the truck had been sitting is a definite red flag.

 

[crash68]

The underground fuel tanks get water leakage and that same thing could of happened with the def,

Unless the water goes down the port that used to fill the underground tank, it doesn't leak in from the ground.
All the underground tanks nowadays are in dual walled tanks with leak detection. It's a federal mandate as to stop contamination of the ground, it's been mandatory for over twenty years now.
Truck stops also need to ensure they're selling a good product as if the DEF or fuel is proven to have caused damage, they'll be on the hook to pay for the repairs.

 

[HighDesertRam]

Did the shop at leadt test the DEF with a refractometer or hydrometer?

Otherwise, I agree with flushing the DEF tank, then refill with fresh. Your initial post said the truck had been sitting is a definite red flag.

No, they did not test the DEF. I will ask them about that.

I had surgery in mid June and was not able to do any of my normal activities like hiking or working out, no lifting over 10 pounds, etc. I didn't do much driving during that period but it was only for about 6 weeks.

 

[Choupique]

flushing the DEF tank, then refill with fresh.

You can remove the fill line from the tank fairly easily and siphon it out from there. Be sure to use clean brand new tubing if you elect to do that.

Fresh def will dissolve deposits up to a point. The best thing is to use it. Some people dilute it to the lower limit of the acceptable range, which requires a good scanner and some work to do without triggering limp faults.

Unfortunately the only reliable way to do it is to remove everything (header, tank, injector) and clean it all, and flush the lines with distilled water, and reassembled and refill.

I'm patiently waiting for the day that these systems are designed conducive to flushing at regular intervals. It would solve nearly everyone's emissions systems problems, dramatically reduce the temptation to delete, and be all around far better for everyone.