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valleybusman
Top Member

USA
798 Posts

Posted - 12/02/2022 :  10:56:41 AM  Show Profile  Send valleybusman an AOL message  Reply with Quote
Have a 2018 Blue bird all American with a Cummins. Bus set off alarms and derated the engine and driver was told to stop the engine. These are the codes 3712, 3714, 3251 and 5278. All related to the DEF system. Please help again.

raymond47
Active Member

Canada
31 Posts

Posted - 12/02/2022 :  11:26:25 AM  Show Profile  Reply with Quote
If you have insite use the code analyzer to help with a full diag
3251 exhaust too hot, something is fueling the after treatment that should not
3712 information only codes active too long
3714 derate information only
5278 def system frozen either really cold where you are or the temp control in the tank not functioning properly
Hope this helps


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valleybusman
Top Member

USA
798 Posts

Posted - 12/02/2022 :  12:00:52 PM  Show Profile  Send valleybusman an AOL message  Reply with Quote
It's really cold but none of the other buses have had issues. I don't have InSite I have JPro
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raymond47
Active Member

Canada
31 Posts

Posted - 12/05/2022 :  02:08:17 AM  Show Profile  Reply with Quote
Sorry should of David temp sensor in tank not working
I will look at Jpro and see if that will help you
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valleybusman
Top Member

USA
798 Posts

Posted - 12/05/2022 :  4:39:28 PM  Show Profile  Send valleybusman an AOL message  Reply with Quote
Bus needed for a run so was asked to check bus out and get to the bottom of the issues. My laptop said the Doser was frozen and had no heater for the DEF. So replaced the relay for the DEF heater and everything went away after bringing bus into the shop. went to move bus out ad warning for the DEF came on. Used laptop and got a 3258 saying no line heater. Checked fuse was good. I did notice 3 diodes. Could those be the issue? What is there another fuse for the system?
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Bluenozer
Top Member

Canada
640 Posts

Posted - 12/07/2022 :  05:16:04 AM  Show Profile  Reply with Quote
code analyzer is on Quickserve not insite and anyone can create an account for QSOL with upto five ESN so one for every EPA up to now

OEM trained in wiring and all engine platforms for over 20 years
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