CCM Posted July 11, 2017 Share Posted July 11, 2017 Working on a 2012 MRU613 mp7 with non-catalyzed system. I have a constant returning code of SPN 5246/FMI 0, SPN 4094/FMI 18. Replaced def doser nozzle. checked egr valve for flow while unplugged. (has slight flow) Checked diff sensor and checked ports for plugging. Not plugged. I can perform a regen and codes become inactive. Truck will return within a few days with same issue. Just replaced Nox sensors due to updated part number and road tested unit (max hill grade is 15%) while monitoring Nox readings. Nox intake always showed 0 and Nox outlet varied between 236 to 510. Anybody have an idea on what the Nox levels should be? Quote Link to comment https://www.bigmacktrucks.com/topic/50447-nox-readings/ Share on other sites More sharing options...
Mackpro Posted July 12, 2017 Share Posted July 12, 2017 (edited) Im thinking outlet should be below 150 but not sure. They only made the spark assisted DPF with SCR/DEF for one year. This Bulletin is for the catalized DPF/SCR but might have some tips in it. Also , software updates help alot sometimes. SPN5394 SPN4094 code.pdf Edited July 12, 2017 by Mackpro Quote Link to comment https://www.bigmacktrucks.com/topic/50447-nox-readings/#findComment-374722 Share on other sites More sharing options...
Mackpro Posted July 12, 2017 Share Posted July 12, 2017 Here's some more info I forgot about. 4094 inducement stra.pdf Quote Link to comment https://www.bigmacktrucks.com/topic/50447-nox-readings/#findComment-374723 Share on other sites More sharing options...
CCM Posted July 12, 2017 Author Share Posted July 12, 2017 @Mackpro, Thanks for the info Quote Link to comment https://www.bigmacktrucks.com/topic/50447-nox-readings/#findComment-374735 Share on other sites More sharing options...
CCM Posted July 12, 2017 Author Share Posted July 12, 2017 Troubleshot for 4094 code. Monitored while performing regen and towards the end of the regen the Nox levels were still at high 200 to low 300. Recommend removing the egr cooler and insp? Quote Link to comment https://www.bigmacktrucks.com/topic/50447-nox-readings/#findComment-374743 Share on other sites More sharing options...
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