DEF Sensor - DSS and Carry On!

[DrPhil]

Guess I am officially the guinea pig, so I wanted to share with the forum my experience with the above. Like many of you, I have lived with angst about DEF sensor failure, so I thought I’d share my experience in the hope that it would help others worried about or experiencing the same.

On Sept. 12, 2021 I was alerted by the IRV2 forum regarding the existence of a Diesel exhaust fluid Sensor Simulator (DSS) that would allow one to temporarily bypass a defective DEF sensor and allow one to proceed to a service center avoiding a dangerous roadside situation and/or costly tow (links below). I thought that such a device might be an inexpensive insurance policy in the event of a DEF sensor failure, so I purchased the parts ($78), programed the board and assembled. Programing was much easier than I anticipated, but fashioning the cable was the tough part (tight wiring inside of a small DB9 connector). The completed device was ready on Sept. 17th, but little did I know that I was going to need the dang thing soon.

Less than 48 hours later on Sept. 19th, DEF sensor failure occurred on my 2017 DSDP 4369 on Spartan K2. This was a real shock as I had babied my DEF system filling it at every fuel fill, etc. for the last 2 years, and at the time, the DEF tank was >3/4 full. Initially the MIL, CHECK ENGINE and a solid DEF lamp came on, and fault codes 3364 DEF QUAL, 1761 DEF VOL, and 3031 DEF TEMP were observed. Shortly thereafter (15-20 min/miles of driving) fault codes 5842 SRC MON and 1569 TOR DER were also generated. Clear 25% derate was observed at the same time via my connected ScanGaugeD looking at horsepower output (typically reached 360 hp at full throttle now 265 hp). Finding a safe place to park, allow the engine bay to cool and my nerves to chill, I powered down the chassis, disconnected the DEF sensor from the chassis harness, and plugged in the DSS (anchoring it securely via zip ties). After re-powering the chassis and starting the diesel, the CHECK ENGINE and DEF lamps disappeared, but the MIL light remained. All 5 of the codes still registered in the dash system as well as the ScanGaugeD, so I used the ScanGuage to to clear. All codes cleared except 3031 DEF TEMP. I then drove the coach and verified no additional codes appeared and normal horsepower returned as well. At my next stop, I shut down the engine and restarted. This last operation cleared the final 3031 fault code.

The next, very important step was to arrange a proper, permanent repair to this temporary DSS fix. Therefore on Sept. 20th, Spartan was called, and they verified the issue as a failed DEF sensor. To my amazement, they had the part and were willing to overnight, CoachNet arranged a mobile service visit to my location, and Cummins Sales and Service in Indianapolis did the actual work in the field.

A huge thank you (acknowledgements below) to all involved that helped me deal with my DEF sensor problem in a super timely manner! I have numerous pictures that I will post soon. PM me if you have questions.

Let’s get out there RV’ing again with confidence!

DSS and Carry On!

Acknowledgements!!!
~ Mark, Vic, Rob, and others (DSS Development Team). Empowered me to temporarily fix in the field. Truly a fun experience building, programming, and deploying the DSS. I say “DSS and carry on” t-shirts/hats should be made!
~ Dave, Spartan. Had the part and was super flexible in how to address issue and ship.
~ Jacob, CoachNet. Owned my problem, and worked with Laura at Cummins and Dave at Spartan to expedite.
~ Laura, Cummins Sales and Service, Field Operations Office, Indpls. Was willing to go the extra mile to jump through hoops at Spartan and CoachNet and arrange for someone to get to my location quickly.
~ Rob, Cummins Field Service Tech. Awesome repair! What a gentleman!

Original article describing the DSS: https://www.rvtravel.com/def-sensor-...und-rvt-1017b/
DSS Build (Uno R2 ATMega256o version - parts for Arduino Due unavailable): https://defsim.myervin.com/using-an-...-def-simulator

[USMCRET]

Great report!

[R.Wold]

An indisputable success story! When all the manufactures and policy makers could do nothing but stall and fail, a few intrepid and talented individuals prevailed. Awesome!

Mine will be in my tool box. I dont need it now but unlike DrPhil, my emissions warranty has expired. Apparently after 1826 days, poor design and manufacturing are summarily excused. At least now I am a lot less likely to be stranded again by this nonsense!

[DrPhil]

Here are some pictures of my Uno board build. Link above to the instructions. As stated before, it was pretty easy to put together and program, but the DB9 connector was very difficult due to the thick wires and tight space. Next I will have some pictures of the install followed by a detailed comparison of the old and new DEF sensor including a dissection of the old.

[DrPhil]

Here are some pictures of the install process - before, during and after. It was necessary to unbolt the DEF pump which sets on top of the DEF tank to gain access to the DEF head. I was surprised that the 'sensor' part (two black plastic tubes) was only one small portion of what is actually a full DEF head. The coiled portion is a heating loop for the winter time. The installer had to pinch off the engine coolant hoses that are attached to these coils to avoid draining/re-filling the engine coolant tank much like we would pinch off oasis summer loop hoses when replacing that pump. Also there is one long tube that goes to the bottom of the tank that is open at the bottom - the DEF pickup point.

[RJ51]

Thanks DrPhil for that info. Just had my def header replaced at Freightliner after waiting 5 weeks for the part. Had ordered the parts for the work around it will come in handy if it goes out again. So it's good to know it works.

[Archer2]

When I get time I’m going to disassemble my Mega 2560 based DSS and re-do the DB9 using 4 short lighter gauge wires soldered and shrink-tubed to the end of the cable. I don’t feel confident with having crammed the heavier gauge wires into that time space. If that works better we might make that part of the instructions.

[Archer2]

Also Dr Phil, the actual 3 sensors (thermistor for temperature, ultrasonic for DEF quality and a different ultrasonic sonar device for DEF level. over-engineer much?) are all contained in the little “foot” that extends a couple of inches horizontally from the black vertical tubes at the very bottom.

[Lt Dan]

Thread Reminder

Just a reminder that soliciting or selling, whether for profit or free is not allowed by Community Rules. A post has been removed for that reason.

[DrPhil]

Originally Posted by Archer2

Also Dr Phil, the actual 3 sensors (thermistor for temperature, ultrasonic for DEF quality and a different ultrasonic sonar device for DEF level. over-engineer much?) are all contained in the little “foot” that extends a couple of inches horizontally from the black vertical tubes at the very bottom.

I’m taking a Dremel to the old sensor tomorrow to see what is inside. Not sure I’ll learn anything, but should be cathartic! (Too small to blow up or shoot to pieces!)

[DrPhil]

Originally Posted by RJ51

Thanks DrPhil for that info. Just had my def header replaced at Freightliner after waiting 5 weeks for the part. Had ordered the parts for the work around it will come in handy if it goes out again. So it's good to know it works.

I don’t understand how I was so fortunate that Spartan had the sensor in stock for my DSDP. I’ve not heard of anyone getting one next day, and it seems your experience is of 5 weeks is quite typical.

[Scott201]

Dr Phil, thanks for this report. I'm assembling a simulator using the same components in your photos. In the assembly/testing instructions it says to plug the assembled device into a USB port and that a flashing light indicates proper operation. I'm getting a flashing amber, but also a solid green light. I'm curious if you tried this test and what your results were. Thanks-

Also FWIW, our Def sensor failed almost exactly a year ago and I was able to get one overnighted to me at that time. We now have a Gen 6.

[Archer2]

Originally Posted by DrPhil

I’m taking a Dremel to the old sensor tomorrow to see what is inside. Not sure I’ll learn anything, but should be cathartic! (Too small to blow up or shoot to pieces!)

Hey Phil. I tried doing that and didn’t get very far. Take my advice and wear a mask over your nose and mouth. I don’t know what the thing is made of but after a few minutes of breathing in the Dremel dust I gave up but I felt sick for a few of hours.

[paulsmi]

Im a newbie on this board so perhaps you could help me understand what was in the post that was deleted. Was someone trying to sell the DSS? Ive looked at all the developer posts but (as much as there is a market for them) none claim to offer the device for sale. Can you help me understand the rules? Thanks.