leehoell Posted July 28, 2015 Share Posted July 28, 2015 got two trucks in shop, both 2011 granite with mp8, keep getting 3226-9 codes abnormal update rate. checked wiring, supply, ground, 120 ohm resistor, all ok. one was at mack dealer and they said they dont really know what causes it, but a new set of injectors usually fixes it. that doesnt sound right. we replaced both nox sensors. any one got some suggestions? Quote Link to comment Share on other sites More sharing options...
Kyle 537 Posted July 28, 2015 Share Posted July 28, 2015 Did you check the wiring all the way to where it goes in to the chassis harness. Over the drive line and top of frame rail a lot or times will rub. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
turckster Posted July 29, 2015 Share Posted July 29, 2015 With this fault there is a loss of communication with the nox sensor. As stated above, check the wiring carefully. Check for damage to the harness, particularly any points that have added equipment. We have a customer that owns many Mack trucks, they routed the pto pump supply hose down the right side of the cab and frame then under the trans. In that area the hose would rub on the wire harness going to the dpf assly causing similar faults. Most of those trucks that were rigged the same were rolling in one at a time with nox and dpf issues. Quote Link to comment Share on other sites More sharing options...
leehoell Posted July 29, 2015 Author Share Posted July 29, 2015 found the problem, accidently put outlet sensor for a cummins on it. looks the same. got new one from mack today, seems to be ok now. while regenning though with vcads, i try to look at sensor parameters and neither nox sensor shows a reading. both show zero. all other parameters read ok, regeant psi, boost, temps. any one else had that problem Quote Link to comment Share on other sites More sharing options...
leehoell Posted July 29, 2015 Author Share Posted July 29, 2015 take that back, got outlet to read, was 510 during regen, then droped to 76-79 at end and when finished. inlet never did read though. Quote Link to comment Share on other sites More sharing options...
Dieselwrenches Posted August 2, 2015 Share Posted August 2, 2015 Inlet won't read ever to laptop. Sensor won't read until they are at a certain temp anyways and 510 is max reading which is fine during a regen. Quote Link to comment Share on other sites More sharing options...
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