DEF head is or isn't?

[jagpot]

Months ago someone one this site said with great certainty that my 2014 Newmar King Aire does not have a DEF head. I can not confirm that. I am unable to find that conversation now but would like some other opinions on this please.

 

[Neal]

Spartan would be the one to ask.

 

[J&JD]

You coach definitely has a DEF head that controls DEF fluid to the exhaust system but I don’t believe it has the sensors that are part of the head ”system”. It’s the sensors that are causing most of the problems not the head itself.

 

[jagpot]

You coach definitely has a DEF head that controls DEF fluid to the exhaust system but I don’t believe it has the sensors that are part of the head ”system”. It’s the sensors that are causing most of the problems not the head itself.

Thanks so much. Maybe it was you that had noted this earlier. I have had the check engine light go off coupled with "Low DEF" messages. No derate has ever taken place. I never know when the shoe will drop but maybe I am not part of this Head failure problem.

 

[MapNerd]

I think the last MH vintages to not have DEF systems were 2010

 

[Old-RV'er]

Yes, 2010, because government mandated 2011 engines would be DEF compliant, or have some kind of system which reduced the pollutants they are/were targeting. Caterpillar, left the RV engine line because of those requirements. Internation diesel, tried with another approach, which did not ever succeed, and finally joined the DEF parade, plus the fines from the government did not help them achieve that goal. I suspect that growing pains early in the effort caused some DEF issues, but it was more than likely, the real "sensor" issues did not start to show up until 2018 or so, because of the Japanese Chip fire, and the subsequent worldwide chip shortage which occurred after that. It did not help the earthquake and tsunami in Japan which destroyed a whole bunch of electronics companies as well in 2011. Some ham radio/electronics companies are still in difficult areas because of that. It takes years to build clean/sterile chip/electronics plants.
Intel is building a new fab plant in AZ, but it's not expected to be online last I heard until 2025 at the earliest, COVID and restrictions/workers will most likely delay that date. I don't know for sure if Freightliner/Cummins powerplants are experiencing this issue to a large degree. Most of the problems are with spartan chassis-based RV's. Someone correct me if I am misinformed. Cummins, I believe has a software patch which will allow no derate, but Red Baron has a fuller explanation. Search this forum for "Def Head Failures" and you will see several threads on the subject, his explanation will be in one of them.

 

[Rich W.]

For a 2014 coach, even if its a mid-2013 chassis, it will have a DEF head, but will have sensors for only DEF temp (to control the tank heater in the event of very low temp to prevent freezing), and DEF level - most likely a mechanical float driven sensor.

The majority of problems seem to be centered around the DEF Quality sensor found in 2016 and later systems. That doesn't mean you wont have problems, but if you do they are easier to address.

Im curious: were your “low def“ warnings a result of a low tank level, and did they resolve with filling, or were they erroneous, and if so, how were they resolved?

 

[jagpot]

For a 2014 coach, even if its a mid-2013 chassis, it will have a DEF head, but will have sensors for only DEF temp (to control the tank heater in the event of very low temp to prevent freezing), and DEF level - most likely a mechanical float driven sensor.

The majority of problems seem to be centered around the DEF Quality sensor found in 2016 and later systems. That doesn't mean you wont have problems, but if you do they are easier to address.

Im curious: were your “low def“ warnings a result of a low tank level, and did they resolve with filling, or were they erroneous, and if so, how were they resolved?

Thanks for your response. In the four times this "LOW DEF" message has gone off the tank was 1/2 to 3/4 full. We simply filled it the rest of the way and turned the engine off,restarted and were fine. It has not happened in a while now but we fill it when we diesel up and watch it drop one bar at 3/4, one at 1/2 and one at 1/4. We try not to get to one bar. We had the NOX sensor replaced but continued to have problems after that. Keeping our fingers crossed.

 

[Rich W.]

Thanks for your response. In the four times this "LOW DEF" message has gone off the tank was 1/2 to 3/4 full. We simply filled it the rest of the way and turned the engine off,restarted and were fine. It has not happened in a while now but we fill it when we diesel up and watch it drop one bar at 3/4, one at 1/2 and one at 1/4. We try not to get to one bar. We had the NOX sensor replaced but continued to have problems after that. Keeping our fingers crossed.

Ive resolved “low DEF” warnings (with 3 bars showing) twice by adding more DEF. Both times (I had two others before I made this connection) occurred early in the morning after overnight temps in the 20’s. DEF is supposed to be ok down to 12 degrees F, when it will start to turn to slush, but I am working on a theory that it may freeze in the lines or on the metal parts of header assembly at temps somewhere above 12 degrees (when the DEF tank heater would not be active) and is resolved by adding relatively warm DEF.

Did either of your episodes occur at low temps? All four of mine did.

 

[jagpot]

Ive resolved “low DEF” warnings (with 3 bars showing) twice by adding more DEF. Both times (I had two others before I made this connection) occurred early in the morning after overnight temps in the 20’s. DEF is supposed to be ok to 12 degrees F, when it will start to turn to slush, but I am working on a theory that it may freeze in the lines or on the metal parts of header assembly at higher temps (when the DEF tank heater would not be active) and is resolved by adding relatively warm DEF.

Did either of your episodes occur at low temps? All four of mine did.

Actually this may blow your theory up. One on the way home from Vegas with outside temps of 114. Other times perfect temps 70-80. The fill seems to answer the call though.

 

[Rich W.]

Actually this may blow your theory up. One on the way home from Vegas with outside temps of 114. Other times perfect temps 70-80. The fill seems to answer the call though.

Yes, my observatios could well be coincidence, and/or it could be a weak or faulty level sensor (float) that gets stuck. But if it gets stuck above empty it should report that level and not “low DEF”, unless the ECM is also programmed to track a gradual reduction in the tank level. I’ll have to investigate that one.

 

[jagpot]

Yes, my observatios could well be coincidence, and/or it could be a weak or faulty level sensor (float) that gets stuck. But if it gets stuck above empty it should report that level and not “low DEF”, unless the ECM is also programmed to track a gradual reduction in the tank level. I’ll have to investigate that one.

Let me know what your research brings up. It certainly is worrisome.