Community Forums

dwaugh10 · 04-23-2025, 08:28 PM

10 miles from home after a trip to Vegas and the dreaded DEF head codes have appeared

I’m 6 weeks out of warranty

I’m hoping Tiffin will give me some help. I’ve reached out to them via email, so I’ll see what they say.

David

777 Driver · 04-23-2025, 10:09 PM

Quote:

Originally Posted by dwaugh10

10 miles from home after a trip to Vegas and the dreaded DEF head codes have appeared

I’m 6 weeks out of warranty

I’m hoping Tiffin will give me some help. I’ve reached out to them via email, so I’ll see what they say.

David

You might want to check your warranty. To the best of my knowledge, EPA required equipment (DEF head), carries a 5 year warranty from your in-service date. Depending on when you took delivery of your 2020 Tiffin, you might be good...or...not.

Take care,
Stu

d23haynes57 · 04-23-2025, 10:14 PM

How many miles? Do you also know start cycles and idle hours? Curious what drives these failures.

Archer2 · 04-23-2025, 11:44 PM

Hi David, sorry to hear of your problem and I hope Tiffin will stand behind their product. As far as Dennis’ desire to know what’s causing the failures (as do I), I am convinced that it is something in the sensor design and not entirely caused by any sort of external factor ie old fluid, out of spec urea percentage, heat, etc.
Think about just the small group that worked on the DSS project as a reasonable facsimile of a random sample. There were basically 5 people with different coach makes, models and engine types but sooner or later every single one have sensor failures (some more than one) with the exact same codes and failure modes. I’m not a statistics expert but that’s got to indicate a pretty high failure probability, right?
My bet at this point is that there is a firmware fault in one of the components common to all the sensors, something like a CANBUS transceiver or driver chip that shuts the chip down for an anticipated fault like an overtemp but fails to restart its normal function when the fault is no longer present.
It has to be something really obscure or Shaw would have by now found it and corrected it, maybe they actually have and just aren’t telling.

shepardmike · 04-24-2025, 06:56 AM

Quote:

Originally Posted by dwaugh10

10 miles from home after a trip to Vegas and the dreaded DEF head codes have appeared

I’m 6 weeks out of warranty

I’m hoping Tiffin will give me some help. I’ve reached out to them via email, so I’ll see what they say.

David

David - did you build a DSS simulator?

d23haynes57 · 04-24-2025, 07:03 AM

Are we talking about the sensor or the head? I'm asking about the life and possible failure causes as there are times I consider upgrading my rig. A dreamer! I am thinking a 45 with 600HP. For my budget I am looking at 2010-2015. As most in that time frame have Cummins engine do I go with the early Non-DEF-SCR engines that have failure issues or go late but then have to deal with this DEF stuff? Or maybe go just a bit older and get DD powered Prevost or Cat powered Newell?

bentjm · 04-24-2025, 07:54 AM

Quote:

Originally Posted by d23haynes57

Are we talking about the sensor or the head? I'm asking about the life and possible failure causes as there are times I consider upgrading my rig. A dreamer! I am thinking a 45 with 600HP. For my budget I am looking at 2010-2015. As most in that time frame have Cummins engine do I go with the early Non-DEF-SCR engines that have failure issues or go late but then have to deal with this DEF stuff? Or maybe go just a bit older and get DD powered Prevost or Cat powered Newell?

I, personally, would go with a unit with DEF vs and earlier unit with the EGR/valve stem issue.

The price to replace a DEF head is much lower than replacing a cylinder head.

Now, if you could find a unit where the cylinder head had been replaced, that could be a different story.

dwaugh10 · 04-24-2025, 11:05 AM

Quote:

Originally Posted by shepardmike

David - did you build a DSS simulator?

Yes, I did build a DSS

dwaugh10 · 04-28-2025, 10:16 AM

Quote:

Originally Posted by dwaugh10

10 miles from home after a trip to Vegas and the dreaded DEF head codes have appeared

I’m 6 weeks out of warranty

I’m hoping Tiffin will give me some help. I’ve reached out to them via email, so I’ll see what they say.

David

Well no warranty help from Tiffin. They said since Thor buyout, warranty is warranty. Also, they are out of stock for the DEF head…hopefully get one in late May.

Archer2 · 04-28-2025, 05:33 PM

Sorry to hear that David. You might give these guys a try. For some reason I am thinking that they are related somehow to Shaw Development. Anyway they might have a replacement for faster and cheaper than Tiffin.
https://durawrx.com/def-header-sensors/
Good luck

FLYAway1 · 04-29-2025, 01:34 PM

We lost ours early this year. We had filled the DEF tank at a Pilot/Love’s - don’t recall- and believe the nozzle was contaminated. We came to this conclusion after talking to a few people who said just use the container DEF not the truck stop DEF.

Anyway, short story even shorter— we took the coach to a yellow freight dealer. They replaced the head and a couple of hoses.

So, an idea if you are in need for a faster repair.

Marsha