DEF concentration low +Emission + check engine

[cliffj]

2020 MA K3 Spartan 500 Cummins I just picked up if Fl. A few minutes into trip DEF low concentration was flashing. Hour or two later emission notice popped up with check engine icon, in orange.
I drove a few hours like this to a freightliner and they cleared all the codes except the DEF code as they weren’t qualified…said Spartan/Newmar dealer needed. I drove 10 hours with only the DEF warning, and then the others came back. I drove 4 hours with all notices and stopped for the night. Check engine icon is orange, not red and not flashing. I have 3 hours in the morning to home and the dealership. Will I make it..? Seller also gave me this magic box to bypass the DEF tank, plug into it and it apparently does something. Will I make it either as is or with the box plugged in?
Semi middle of nowhere is part of the problem.
Please and thank you.

[LWBAZ]

I suspect what the seller gave you is a DEF Simulator.

When the DEF head fails, it starts reporting an erroneously low level of DEF in the tank, DEF temperature out of acceptable range, and DEF concentration (urea vs. deionized water) out of range. There is typically nothing wrong with any of those three parameters, but the Engine Control Module (ECM) sees the erroneous errors codes and will only let you drive so far before it starts de-rating your engine power & speed.

If that happens, you can unplug the four-wire connector coming off the DEF head and plug in the DEF simulator device. The simulator will tell the ECM that all is well and you can continue on without the de-rate. You do need to visually monitor the DEF level in the tank and ensure you keep enough DEF in there to not run out.

And of course you'll want to get to a Cummins repair center as soon as convenient so you can have the bad DEF head replaced.

[Archer2]

Cliffj, you say you just picked the 2020 MA up? It is possible that the DEF may be old and out of the spec for 32.5% urea due to age. If so, just topping it off with fresh DEF May clear the code and you may not have a bad sensor. You also say that it started “flashing low DEF concentration”. Do you mean to say “low DEF level”? Those are two different things but I don’t think your Coach actually has any specific low DEF concentration light. I think you would get a Check engine light with a specific code.
Is the “magic box” plugged in yet? If it isn’t you should go ahead and do that. It will prevent you from being derated at an inconvenient time & place so if you are stopped in a place where you can get it plugged in now you should do it.

[tqqest]

CliffJ,

I had this exact issue on my 2020 DS4369 on a Spartan chassis. I chased this for a year with Spartan. They had me try so many things, none of which worked.

It only happens after driving for several hours, was a “Low DEF concentration” message, then the check engine light, but did not set a permanent hard code, and the message and lights would go out the next morning when the engine was cold. It never derated me and had nothing to do with the DEF.

It turned out that the valve that controls the flow of hot engine coolant thru the DEF tank was stuck open. It is only supposed to be open when the DEF is close to freezing.

With it always open, the hot coolant flows non stop and overheats the DEF in the tank. Once the DEF gets too hot, mine would get 150 to 175 degrees, the DEF quality sensor can no longer function. The next morning all is cool, and everything functions just fine until the cycle starts over again.

I would try pinching off the hot coolant line at the DEF tanks with a hose clamp, and then see if it still happens after a long drive.

[777 Driver]

Originally Posted by tqqest

It turned out that the valve that controls the flow of hot engine coolant thru the DEF tank was stuck open. It is only supposed to be open when the DEF is close to freezing.

With it always open, the hot coolant flows non stop and overheats the DEF in the tank. Once the DEF gets too hot, mine would get 150 to 175 degrees, the DEF quality sensor can no longer function. The next morning all is cool, and everything functions just fine until the cycle starts over again.

Tad, it's interesting that you mentioned this. LWBAZ, who posted above, started this thread:

https://www.irv2.com/forums/f278/add...ve-547304.html

that describes his process of installing a quarter-turn ball shutoff valve in the coolant line to positively shut off coolant flow to the DEF tank when the weather was warm enough that heating the DEF fluid was clearly not necessary.

Although he didn't describe any observed problem with the DEF overheating, he felt that the potential of that was great enough that he took proactive action to prevent that.

Take care,
Stu

[tqqest]

Hi Stu,

Yeah, I remember that post now! I talked to Spartan many times, and that possibility never once came up. I even told them it always happened more quickly on 90 degree + days.

They kept insisting that it was a phantom software issue and to ignore it, as it always went away the next day and never left me stranded. I dumped my DEF 4 times, and tried 5 different brands of DEF in the process. I even had it checked out at NIRVC, and since there was no hard code set, and it didn’t show up when the mechanic took it on a 1 hour test drive, they couldn’t figure it out either. I finally traded it in to Tom Lindstrom, and his service tech Mike was able to get it to a service center that figured it out after 3 weeks!

Glad to have no DEF issues on my 2022 Freightliner! 🤞

[cliffj]

Mine has never gone away except when plugged into the magic bypass box. Check engine light never went away however. Should I be worried about going into limp mode if I can’t find an immediate solution when traveling? I don’t think mine is a temp thing as it has always been there on start-up regardless of the temperature.
Regardless, this mountain aire is an awesome coach.

[777 Driver]

Originally Posted by cliffj

Mine has never gone away except when plugged into the magic bypass box. Check engine light never went away however. Should I be worried about going into limp mode if I can’t find an immediate solution when traveling?

When the DEF System Simulator (DSS) is installed, the DEF gauge should indicate 3/4 full, regardless of the actual quantity. That's a "tell" that the DSS is functioning. That's also the reason that it's important to visually confirm the DEF quantity with the DSS installed.

When my DEF head failed, it took three engine run/stop events after the DSS was installed for the check engine light to self clear.

At least, that's how it all worked for me on a Spartan K2 chassis.

Take care,
Stu

[cliffj]

I have 2 questions…has Newmar/Cummins/Spartan actually fixed the problem yet, better sensors or whatever, or is it still a work in progress? And if I know there is plenty of good DEF in the tank, can I just keep driving with the magic box attached? I am close to Transwest in Kansas City but I have zero faith in their ability to fix it if the current status is “maybe”. I just want to travel in my new-to-me coach without the angst of limp mode possibilities.

[777 Driver]

Originally Posted by cliffj

I have 2 questions…has Newmar/Cummins/Spartan actually fixed the problem yet, better sensors or whatever, or is it still a work in progress? And if I know there is plenty of good DEF in the tank, can I just keep driving with the magic box attached? I am close to Transwest in Kansas City but I have zero faith in their ability to fix it if the current status is “maybe”. I just want to travel in my new-to-me coach without the angst of limp mode possibilities.

Probably, YES.

Does your DEF gauge show 3/4 full? That's a 'tell' that your DSS is functioning.

Why do you think that Transwest in Kansas City is unable to replace the failed DEF head?

It's your call.

Take care,
Stu

[ronboatplane]

Originally Posted by 777 Driver

Probably, YES.

Does your DEF gauge show 3/4 full? That's a 'tell' that your DSS is functioning.

Why do you think that Transwest in Kansas City is unable to replace the failed DEF head?

It's your call.

Take care,
Stu

The simulator does not interfere with pollution control. Instead it generates the computer codes of a proper functioning def head as others have pointed out including the code of a 3/4 full def tank. Meanwhile the chassis computer continues to supply the def fluid necessary to maintain emission standards. The experiences of members here have found the def head malfunction caused sensors to stop reporting quantity of def fluid in the tank . This starts an engine derate process which will leave you stranded after a fixed miles period. The simulator is a temporary solution to the def head malfunction so you may get to a maintenance facility and replace the def head which is now on its 7th edition. You could continue to travel indefinitely as long as you keep the proper concentration and quantity of def fluid in the tank, but that is highly discouraged. Driving for an extended period might be interpreted by the feds as intent to violate the law.
The lack of available replacement heads has left many people stranded in precarious predicaments especially for the RV over 55 crowd which is most of us. This temporary solution allows us to travel safely giving us piece of mind that we won’t be stranded for months waiting on a new def head to become available. We were between a rock and a hard place until someone on this site showed us how to continue safely on our journey while a new def head could be found and installed. Use your judgment and conscience to determine how long you should go with this temporary fix while you safely travel out of a predicament that many of your retired peers have found themselves in through no fault of their own.

[Robert1959]

Interesting reading, I have a 2020 4369 DS with the fluid quality code issue. Usually after about 30 to 60 miles into a trip. I suspected it was a temp issue and have been insulating the tank from the exhaust system. I need to check temperatures after startup. I think a ball valve would be a great idea. I bought the DSS box and dumped multiple tankfulls of this crap on the ground. Wasted time at Cummins (they stated, nothing wrong when the code is on the dash). Total BS.

[Capt. Bill]

Two weeks ago I had the same issues- Low DEF Quality & Low DEF messages on my dash as well as 'Check Engine' light came on. I thought it was the dreaded DEF Head issue, but being on a 2013 FL chassis- which aren't known to have the DEF Head issue in that year range, I thought otherwise.

Took it to a Freightliner /Cummins shop & they diagnosed it as a faulty DEF dosing sensor in the engine exhaust- monitors PPM of sulphur at engine exhaust & sends dosing rate to DEF pump. Not a cheap fix @ $2,300 for parts & labor. So far it appears to have fixed the problem but time will tell.

Happy Trails