T770 Dosing Error codes U003031-21, U004337-12, U004337-07

[mknsawdust]

I have a 2019 Bobcat T770 that has been giving me 3 primary error codes related to the Def Dosing Emissions process that I cant figure out and need some more experienced advice on the problem.

U00433707 Dosing valve tip temperature fault
U00433712 Dosing valve tip temperature fault
U00303121 DEF temperature fault

These 3 codes pop up pretty consistently and yes if they pop up often enough then i do lose power. I can power off and reset and its ok for a while but eventually the codes pop up. I have spent many hours researching the issue but I dont find hardly anything on what the root cause of the problem is and how to fix it. The only thing I could find what a possible problem with the Dosing valve maybe being corroded with crystalized DEF fluid or clogged or not functioning properly. I tore apart the exhaust to get to the dosing valve and removed the DEF dosing assembly unit to inspect it. I didnt see anything obvious that looked like it was preventing it from functioning but i cleaned it along with the NOX sensor and another sensor that both protrude into the exhaust. I reassembled everything and I still get the codes popping up.

The next thing i tried was to replace the dosing module itself thinking maybe its defective. That part number is listed below. Again this did not fix the problem. The codes still pop up.

7248682 Dosing Module

So if the problem isnt the dosing valve or the assembly, or the sensors in the exhaust, what else would be causing the error codes?? There is plenty of DEF fluid in the tank and I always keep it fairly full. Is there something else that could be preventing DEF fluid from flowing to the dosing valve? If there is, wouldnt i be getting a different error than one related to dosing valve? If it was a DEF pump problem i should be getting a different code.

Any help would be appreciated. I'm at my wits end with this. LOL.

 

[mknsawdust]

Since i had no replies to my post i neded up taking the skid steer into the dealer. I wanted to post an update and hopefully someone else can learn from my findings.

After taking it in, they informed me the emissions system has a 5 year warranty on it that was good until October. That was a surprise.

After running diagnostics on it, they discovered the sensor in the DEF tank was reading a temperature of -7 degrees. Since the air temp is around 80 degrees right now they knew this wasnt correct. Since the sensor was reading a temp, it wasnt throwing an error code. The other error codes were being thrown because of the huge difference between the DEF tank temp reading and the Dosing valve temp reading and the computer knew there was something not right.

Under the warranty, they replaced the entire tank assembly and all components inside the tank. Out of pocket this would have been a $1400 part by itself not including the labor.

After replacing the DEF tank assembly everything checked out fine. I got it home and used it for several hours without any codes popping up so thats a good sign.

All along the problem appears to have been a temperature sensor in the DEF tank. Go figure. No codes pointed to that as the problem at all.

 

[brdgbldr]

Glad to hear you got it fixed and under warranty no less.