ISB6.7 DEF HELP

[JimT]

As far as flashing an incal to clear the code... not sure that's the best way. I haven't tried troubleshooting this issue so my knowledge might be limited here, but there should be a way to clear the code(s) with insite and reset the aftertreatment counter(s) that result in the derate. As far as I can tell, flashing the file is simply clearing the history of occurrences. Like a big reset button. Once clear the counters start tracking the code(s) again until they hit the threshold and apply the derate.

So the problem only pops up when the vehicle is moving? To me that points directly to the tank/pump OR a bad/loose wire/connection.

I'd double check all the wiring to/from the pump and doser valve. Also check all you battery cables and grounds. Not sure about your engine, but my 2250 had a dedicated fuse holder and wiring harness inside the battery box coming off the positive battery cable then going directly to the DEF unit. Check those inline fuses for defect or tarnish on the blades. Check those wires for loose connections. Check the pins inside the connectors for corrosion or bad connections. The system is often abbreviated "DCU" for Dosing Control Unit (or something). Annnnnd that brings me to the last electrical possibility... The DCU could be bad. Though I'd bet on a bad connection to/from the DCU before suspecting the unit itself. Insite/Quickserve should have detailed troubleshooting information for this system and you should be able to pull up a wiring diagram for your engine (including the aftertreatment) on Quickserve.

As for the pressure sensor being in the doser valve... I'm not sure if that's true or not. But it wouldn't actually matter WHERE the sensor is located since the CAUSE of the lack of pressure can be anywhere.

(01-20-2021 )lastmanstandin31 Wrote:  Problem is def system will not prime half the time and throws pressure codes and def input line codes every day which derates the truck.

In my opinion it sounds like you need a new pump or tank (or both if they are an integrated unit).

BTW, I've heard that it's possible to lessen or disable the derates via legal programming while still keeping the system operational. Maybe that's an option until you can scrape up enough money to replace the pump? Just throwing that out there as an alternative. No one here will advocate for the removal of a functional system and unless you've been having a lot of other DOC/DPF/SCR issues then maybe it's better to keep the system intact and well maintained?