DEF Head BS

EmpirE231

EmpirE231

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So I'm pretty sure I'm dealing with the "def head" issue on our new to us RV. On the most recent trip to Glamis, I drive the 110 miles or so to red earth to fuel up... everything is fine, shut it down and fuel up. I go to fire it back up, and get check engine lights, a DEF light blinking on the dash... and I look at my fuel gauge / def gauge and the DEF is blinking red showing it is empty (but it is full) I start freaking out... drive over to the 91 pumps to get fuel for the toys and start debating whether we go home or continue... I shut off the chassis breakers, and start banging on stuff on top of the DEF tank... I fire it up 10 minutes later and everything is back to normal! Jam to glamis... all good. We fire up to head home and everything looks good... I make no stops and drive straight home... within 10 minutes into the drive, the DEF gauge went from full, down to 1 bar... but it was still green and no check engine BS. Made it home... park to unload! as soon as I fire it back up to move it and park it... all the BS comes back.

So.... Is this a DIY type of fix? or does it need to go into a shop? can a mobile technician fix this? what am I looking at to fix this BS $?

RV is a 2011 American coach revolution, spartan chassis, 450 cummins w/ 25k miles

 
I had a heater go bad on my DEF tank that caused a check engine issue on my 2011 F250....it was covered under warranty. Could be a sensor going out. 

 
A guy in our group had the low DEF light come on, tank was full. Goes into limp mode and he limps into the dealer. Guess the sensor that tells the computer the tank is empty likes to go bad. It was on his Chevy and he could see the tank was full.

That next trip I am driving home in my FORD, that you cannot see the tank and on my trim model it doesn't even have a gauge to tell you how much DEF you have in the tank. Well it tells me I am 100 miles from running out. I do the calculation real quick I am 75 miles from home so all is good. Pick some up later in the week... 10 miles later I am now 75 miles from empty. So I stop buy a box and put it in. Back on the road I go, 10 miles later it is still telling me I am almost out of DEF.  Well I made it home before it went into limp mode.  I get ready to find a place I can take it in when I do a quick google search.

With my truck you add one box of DEF at each oil change, until the 100 mile warning comes on, at that time add two boxes of DEF. Only way to reset is to fill it all the way up. 

 
Should be covered under under emission warranty,. BOSH holds the design and patent on the DEF system thus very manufacture is having major DEF sender issues in the diesel industry.   The unit will eventually derate and not function because it believes it is out of DEF fluid. Freightliner has a temp bypass fix for certain s/n ranges  until they have hare a recall campaign to address it . Other manufactures have new sensors, however they need to be ordered by a dealer with t a s/n attached to it. While other manufactures can only receive one per-day no matter how many they have on order for downed units.

 
Tatum Sand Demon said:
Should be covered under under emission warranty,. BOSH holds the design and patent on the DEF system thus very manufacture is having major DEF sender issues in the diesel industry.   The unit will eventually derate and not function because it believes it is out of DEF fluid. Freightliner has a temp bypass fix for certain s/n ranges  until they have hare a recall campaign to address it . Other manufactures have new sensors, however they need to be ordered by a dealer with t a s/n attached to it. While other manufactures can only receive one per-day no matter how many they have on order for downed units.
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wish it was under a warranty, but the coach is a 2011.

Spartan said a new DEF head is $800.  Just wondering if this can be done DIY, of if it should go to a shop.  Also wondering if the new units are more reliable

 
Ive had similar problems on an ISX15 and a PX9, both were the sensors in the tank, very common problem. At the time of the second one there was an 8 week backorder... Ended up on a hook (so to speak)..

IMG_7129.jpeg

 
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I didn’t think the DEF head issues went back that far to 2011. Everything I’ve read seems to be on much newer engines. Wondering if you have a simple sensor issue or perhaps lose wire on a sensor? 

 
Don't fire the parts cannon without proper troubleshooting.  Also, some DEF level sensors work by sonar, and require dead space at the top of the tank. If you overfill them it can't read the ping, and can trip a code.

 
1HasBeen said:
Don't fire the parts cannon without proper troubleshooting.  Also, some DEF level sensors work by sonar, and require dead space at the top of the tank. If you overfill them it can't read the ping, and can trip a code.
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Good point, I've never had one be intermittent, when they failed it was instant and permanent. 

 
1HasBeen said:
Don't fire the parts cannon without proper troubleshooting.  Also, some DEF level sensors work by sonar, and require dead space at the top of the tank. If you overfill them it can't read the ping, and can trip a code.
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So is it best practice to never top off these DEF tanks?

Attached are photos of the DEF tank area... is this enough space to replace it without dropping the tank?

IMG_8192.jpgIMG_8190.jpgIMG_8191.jpg

 
Dockmaster said:
I didn’t think the DEF head issues went back that far to 2011. Everything I’ve read seems to be on much newer engines. Wondering if you have a simple sensor issue or perhaps lose wire on a sensor? 
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Spoke w/ spartan and he said not as common on these older units (4th generation?) but somehow mine went bad.  He said the code is regarding the tank level sensor, which makes sense considering it is full, but telling the system it is empty. 

He said the replacements available are 5th generation, which include quality sensors.... just sounds like more crap to go wrong.  would be nice to be able to find an older generation. 

 
EmpirE231 said:
So is it best practice to never top off these DEF tanks?
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Lots of opinions on this, but that is what I do. The only time I fill is if I am on a long trip, and using DEF at a faster rate. Otherwise, I add a jug when the level warning comes on. DEF does age, and the rate increases pretty substantially with temperature, and rigs that sit around a lot run that risk. A refractometer can at least verify the urea percentage.

 
You can just pee in the tank to fill it. Urea=urine. 
 

Take it easy, that was a joke. 
 

We’ve had exact same issue with the sensors on our Excavator. This said full, but it was at 1/4. Went into limp mode and shut down. Mechanic had to Replace the whole sending unit/sensor module and cleared the code and it’s back to normal. The sensors have been going bad so much that they’re on back order a few months. 
 

Same setup as they are all made by the same company. It’s all junk. 

 
1HasBeen said:
Don't fire the parts cannon without proper troubleshooting.  Also, some DEF level sensors work by sonar, and require dead space at the top of the tank. If you overfill them it can't read the ping, and can trip a code.
Click to expand...
so funny update... still waiting on my new DEF head to arrive... so over the weekend, I siphoned out about 3-4 gallons of DEF.  Unplugged the sensor... disconnected the chassis batteries etc.  Turned key in the on position, and noticed it only had 1 fault code in the memory instead of 3.  Fired it up and a few seconds later all codes went away.  Def gauge is reading 3 out of 4 bars.  I cycled it a few time, and issues haven't came back yet.

Might take it around the block a few times to see if anything acts up.  If not, I'll just hold on to the new DEF head and replace it if issues come back. 

 
we have had some luck putting them in a pot of boiling water for about 30 min to "clean".  we have TONs of issues with these POS at the rental yard. and the backorder on these parts kills us. we use a turkey deep fryer set up.

 
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