DEF Head Failure

[Johninar]

Originally Posted by lce3

One more DEF head failure. Currently waiting for part to be sent from Spartan to our local Cummins service center.

A Cummins service advisor told us to avoid truck stop DEF because it can be dirty so we were feeling guilty for not knowing better. - Good to find out it probably wasn't something we could have avoided.

Grateful for all who have shared their experiences and solutions on this thread.

Your "service advisor" is spreading Internet myths with that. I believe it's an attempt to deflect from Cummins being at fault (they spec what DEF header is used)
Truck stop DEF is probably the best. It's tested and the volume pumped keeps it fresh.

[LeslieGary]

Add us to the list of those with a DEF head replacement. I say replacement versus failure as we we had a couple of episodes of warnings (alarm and yellow warning light) that came and went, but never showed an issue I associated with DEF. In all honesty, I was not aware there was a DEF head or that its failure could stop you dead in your tracks. We drove several hundred alarm free miles since those alarms without incident. (Yes, I agree, ignorance is bliss...)

While I don’t recall the exact error message (I believe it was an exhaust message, but no mention of DEF) I did ask our local Cummins dealer to check the codes during servicing.

Long story short, based on the codes, Spartan shipped a new DEF head and all was covered by warranty. I was able to look at the old part; it had a blue cap. The tech did not know what part of the head failed. I am thankful to have avoided a limp mode episode and will watch the codes more carefully in the future.

For those curious about where we get DEF, 95% of the time we fill our DEF tank when refueling at Pilot stations. As I don’t have any evidence this could be related, I’ll likely continue with bulk DEF, but will perhaps be more discriminating about pump condition in the future.

[Jbc37]

Two days ago Tiffin told me it might be 3 weeks. This morning got the sensor from Tiffin, overnight delivery. it is 22″ long, plus the pig tail…appears 21″ will be inside the tank. no idea what “GEN’ it is. “Sensor kit 325-0086-22-k” is on the package….Ebay has one that appears identical but with 13-k on the end. google search turns up little…Anyway, I have my weekend project set up now….LOL.
2020 37AP Bus

[Ljwt330]

Originally Posted by Jbc37

Two days ago Tiffin told me it might be 3 weeks. This morning got the sensor from Tiffin, overnight delivery. it is 22″ long, plus the pig tail…appears 21″ will be inside the tank. no idea what “GEN’ it is. “Sensor kit 325-0086-22-k” is on the package….Ebay has one that appears identical but with 13-k on the end. google search turns up little…Anyway, I have my weekend project set up now….LOL.
2020 37AP Bus

Without knowing how your communications were conducted, it appears two different things were involved.


Tiffin told you it might be three weeks. That is consistent with what we've been hearing regarding a replacement DEF head. However, you received a new DEF sensor, not the entire head assembly. One could conclude that the key part that needs replacement, the sensor, can be dispatched much sooner than a complete DEF head.


Now, why you got a sensor early vs someone who is still awaiting a compete DEF head is something we cannot determine from your post alone. It is curious, however, because if a stranded motorist can get quick relief by asking the right question, that would be important information.

[ekim]

Originally Posted by Jbc37

Two days ago Tiffin told me it might be 3 weeks. This morning got the sensor from Tiffin, overnight delivery. it is 22″ long, plus the pig tail…appears 21″ will be inside the tank. no idea what “GEN’ it is. “Sensor kit 325-0086-22-k” is on the package….Ebay has one that appears identical but with 13-k on the end. google search turns up little…Anyway, I have my weekend project set up now….LOL.
2020 37AP Bus

Interesting. Tiffin told me that I need to be in a no start situation stuck on the side of the road to be considered for a sensor. I'm trying to see if I can hook up a Freightliner tank and sensor instead.

Who did you speak to at Tiffin in order to get help?

[hcarmon1]

Add me to the DEF sensor failing. Spartan says they are on back order. Now sitting waiting on the part with stop engine light on. Have always used bulk DEF from fuel stops and never let light go over 3 lights. Have to be in MN the first of Sept. so have fingers crossed that the head will come in and Spartan will get someone to install without the coach being towed.

[mobbedstude]

Our Bluebird bus now has 6800 miles on it, and the 3rd def head just failed. We replaced the last one in December of 2020 and did not let the vehicle sit without driving weekly. After talking to the warranty department, I found out that Gen 6 heads are now considered faulty. They are on Gen 7 now, and you don't get the entire head unit, just a sensor to replace. 3 month lead time, as our small business will sit idle and lose money day by day because of this unbelievably ridiculous scenario.

We are debating having the DPF system deleted. Sorry EPA, we cannot continue to lose out on business for your gains.

Does anyone know how many miles you can go from the first warning lights to a derate? I'm also curious how the DPF system knows that you are driving - I read that you can try disconnecting ABS fuse and Speed sensor to trick the vehicle into thinking its idle. But I'm pretty sure Cummins thought about this and has programming in place to prevent people from bypassing like this.

[R.Wold]

Originally Posted by mobbedstude

Our Bluebird bus now has 6800 miles on it, and the 3rd def head just failed. We replaced the last one in December of 2020 and did not let the vehicle sit without driving weekly. After talking to the warranty department, I found out that Gen 6 heads are now considered faulty. They are on Gen 7 now, and you don't get the entire head unit, just a sensor to replace. 3 month lead time, as our small business will sit idle and lose money day by day because of this unbelievably ridiculous scenario.

We are debating having the DPF system deleted. Sorry EPA, we cannot continue to lose out on business for your gains.

Does anyone know how many miles you can go from the first warning lights to a derate? I'm also curious how the DPF system knows that you are driving - I read that you can try disconnecting ABS fuse and Speed sensor to trick the vehicle into thinking its idle. But I'm pretty sure Cummins thought about this and has programming in place to prevent people from bypassing like this.

First, disconnecting the speed sensor only works on vehicles with manual transmissions. It will disable an automatic. I haven't heard about the ABS fuse - got a link to info on that?

Second - don't confuse the DPF system with the DEF system. They are both “after treatment” but are separate systems. DEF failures don't affect the DPF, and cant be resolved by doing anything with the DPF, including forced regens or deleting the it.

With respect to how far you can drive, it appears to be time based with derate accelerated by more ignition cycles, extended idling(over one hour), and fueling without re-filling the DEF tank, and with a bad level sensor it would think you didn't fill it. And as you probably know, derate is incremental starting at 25% and ending in the dreaded 5mph limit. So while you can sometimes make to to a shop if you are close enough and don't turn off the rig and don't idle and don't refill the fuel tank, you really can’t use the vehicle for anything else.

Lastly, if you are desperate, there are shops in Canada that say they can and will disable the derate function in your system without removing any components. The one I contacted said they can do it over the internet with a laptop hooked to the j1939 port and its around $2,500 plus $300 rental of the laptop interface if you don't have one. PM for details. I haven't had it done so I cant offer any information on the results.

This is the email I received from them:

“With the cummin's we are able to do the programming remotely.
If you have or have the means of getting a hold of a Nexiq USB link device, we use that as a communication link between a laptop and the truck. If not we do have laptop's and Nexiq device kits we can ship to you for the use of programming. The laptop kit fee is $299.00USD and that covers shipping to and from your self, and the use of the laptop.
The price is$2500USD
If you have any questions, please give us a email back or a call Monday to Friday 8PM-4:30PM Pacific time.“

[Arty1313]

The last 3 times I have been out I have had DEF failures, 1st a Doser Valve replaced, second Head Sensor replaced, and Third a Doser pump and Doser valve replaced again, still loosing pressure, Coach is at the shop where it has been for the last 2 weeks, tomorrow they said a Cummins engineer would get involved.
I have lost a lot of money and vacation because of this and the Coach is still 4 hours from me.
RVing has seized being fun