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Suggest separate topic for Regen systems.

2011 GU713 MP7. Truck in 5mph derate. Had SPN-5246-O, SPN-4094-14. Tested everything I could with PTT, EGR, turbo, doser, etc. Use scope to inspect SCR catalyst, checked/tested/changed DEF fluid, Cleared codes. 4094-14 would not clear, did multiple regens including sublimation regen, code would not clear.  I am not sure on Mack regen temps but they seem low(see attached). Nox sensor readings in PTT always show "0". If I use JPRO Nox sensor readings are greyed out. Then says "DEF quality being Evaluated, Engine in derate, 5mph Removed", perform regen again= Same. Test drive over 30 miles= Now has SPN-4094-1. Cycle key. Now back to derate, SPN-4094 gone but now has SPN-4094-18 and 5246-0.

Sublimation regen.jpg

Regular forced regen.jpg

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The 4094 and 5246 codes seem to always come together. We had 3 of our truck go down in one day due to these same codes. Cold weather seems to make them happen more than the summer. Poor DEF quality, bad NOX sensors, DEF doser not spraying enough or in the worst case a bad SCR box due to coolant or oil contamination from a past EGR cooler or turbo failure. On your year model the regen temps should be around 625 T1 and 880 on the T2 . As long as the T3 is higher than T2 your probably ok. Main thing Is T2 being 880 or higher. . ( Newer common rail engines have much higher regen temps ). You will usually never see a NOX reading during a regen till the last couple of minutes. Engine fuel pressure should be around 65 psi during a regen . Years ago we used to start a regen with tech tool , unplug the interface adapter (vocom) from the truck and back out of the regen screen plug back up to the truck and go into the screen where you could pick any sensor to view, I think it was Sensor Monitoring something like that , we could pick the NOX inlet and outlet  and watch it while the truck continued to regen . I have all that stuff written down somewhere in my tool box . I’ll see if I can find it tomorrow 

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Ok, I found this quote on another post, Pay attention to boost pressure says 8-12 without DRV valve. This truck has a DRV valve and is only showing boost 1.25 PSI during regen. Towards the end of regen outlet NOx showed 510ppm, after regen and hold throttle floored at went down to 28ppm and that crept up to about 170-200.

 

""First go into the scr system test, There will be an scr inducement reset. Perform that, Then make sure you perform the scr learned data reset for the parts already put on. Sometimes when you have the inducment to clear on the 2010 emission products it may take 2 back to back regens. What you should do is command a regen with tech tool. Then once the regen idles up and starts on its own disconnect the com box either from the computer or from the 9 pin diag connector. You will get an communication error, Plug the com box back in and click okay and click back to go to the main screen in test. Go to sensor monitoring and select the following, Boost pressure, intake air temp, Egr diff pressure, egr mass flow, Ex gas temp, DPF 2 and 3 temp, Def pump pressure, Def doser, and outlet nox, You will want to make sure that the egr dps is staying close to its key on engine off reading which on the older style sensors is plus or minus .3, new style is .1. If that is okay, With out the DRV valve these run between 8-12 psi of boost during the regen. Make sure your t2 and t3 are running around 850+, make sure your def pressure is staying around 130 and not dropping out. Then the biggest thing is outlet nox, You will not be able to view inlet nox on this truck. We used to be able to years ago and they took that function out. Once the regen is complete, Hold the throttle pedal to the floor for about 30-40 seconds and let up, Watch the outlet nox reading. it should be below 100. The lower the better. The placing the throttle to the floor is a method to blow the extra hydro carbons out from the regen. If all of that checks out then you should be good to go and the fault should be inactive, If not then run another regen. Please let me know if you have any follow up questions on this. Thank you.""""

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Ok, I found this quote on another post, Pay attention to boost pressure says 8-12 without DRV valve. This truck has a DRV valve and is only showing boost 1.25 PSI during regen. Towards the end of regen outlet NOx showed 510ppm, after regen and hold throttle floored at went down to 28ppm and that crept up to about 170-200.

 

""First go into the scr system test, There will be an scr inducement reset. Perform that, Then make sure you perform the scr learned data reset for the parts already put on. Sometimes when you have the inducment to clear on the 2010 emission products it may take 2 back to back regens. What you should do is command a regen with tech tool. Then once the regen idles up and starts on its own disconnect the com box either from the computer or from the 9 pin diag connector. You will get an communication error, Plug the com box back in and click okay and click back to go to the main screen in test. Go to sensor monitoring and select the following, Boost pressure, intake air temp, Egr diff pressure, egr mass flow, Ex gas temp, DPF 2 and 3 temp, Def pump pressure, Def doser, and outlet nox, You will want to make sure that the egr dps is staying close to its key on engine off reading which on the older style sensors is plus or minus .3, new style is .1. If that is okay, With out the DRV valve these run between 8-12 psi of boost during the regen. Make sure your t2 and t3 are running around 850+, make sure your def pressure is staying around 130 and not dropping out. Then the biggest thing is outlet nox, You will not be able to view inlet nox on this truck. We used to be able to years ago and they took that function out. Once the regen is complete, Hold the throttle pedal to the floor for about 30-40 seconds and let up, Watch the outlet nox reading. it should be below 100. The lower the better. The placing the throttle to the floor is a method to blow the extra hydro carbons out from the regen. If all of that checks out then you should be good to go and the fault should be inactive, If not then run another regen. Please let me know if you have any follow up questions on this. Thank you.""""

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14 hours ago, Mackpro said:

https://static.nhtsa.gov/odi/tsbs/2013/SB-10054292-5095.pdf this Bulletin might still apply even though yours is not a MRU/leu

Thank You! we finally got it to clear yesterday. Yet I am apprehensive it may return. Earlier in our diagnoses I found a TSB stating if it had original part# NOx sensors to replace with current part number, Truck had one new part # NOx sensor on inlet and old part # on outlet so we replaced the outlet, did multiple regens again and those codes would not clear. Took Truck on another 30mile test run at highway speeds and 14miles in light went off and code cleared. 

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