Mickey603 Posted February 6, 2016 Share Posted February 6, 2016 So, I was lucky enough to get this 2011 LEU Mack with the MP7.Note: Using Tech Tool I was told it had a code of ( SPN:5246 FMI:16 )(SCR system fault detected – Warning fault - Engine derate) at one time which i understand to be a derate to 55mph with a SCR issue.The truck has at this time, ( SPN:5246 FMI:0 )(Severe SCR system fault detected - Severe engine derate to 5MPH) currently with ( SPN:5394 FMI:5 )(Aftertreatment DEF doser and/or Aftertreatment DEF dosing pump assembly) & NOx Sensors Reading to high. I'm guessing the NOx are to high because on the doser valve test, I removed it & ran SCR test & nothing came out. No fluid going into the system will result in high NOx as I understand.Any Help Appreciated. Thanks 2 Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/ Share on other sites More sharing options...
Macktech689 Posted February 6, 2016 Share Posted February 6, 2016 Make sure the DEF tank is not empty and that all the lines are connected and not damaged. The pump pressure should be 126 to 135 psi and remain steady for several minutes. If there is no dosing during the tests I would suspect line is pinched or the pump isn't priming. Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-323294 Share on other sites More sharing options...
j_martell Posted February 6, 2016 Share Posted February 6, 2016 I got similar errors Friday afternoon....2011 GU813 MP7-405M....dropped it off at Mack, gave them the errors I got off the guard dog, the young fella writing the service order seemed to know what I was gonna say.....Already had the doser replaced once a few years ago. Codes were 128 5246 15 and 128 4094 18I googled them and got a error code book with descriptionsOne has to do with DEF quality, which is odd, we get the same fluid all the time and store it in the shop. Bu, I was gone for about a year, and I'm not sure what happened. I know the granite hadn't been greased in quite some time.... Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-323299 Share on other sites More sharing options...
Mickey603 Posted February 6, 2016 Author Share Posted February 6, 2016 (edited) Big Dog, Im not showing any pressures. See attached Photos. Edited February 6, 2016 by Mickey603 Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-323310 Share on other sites More sharing options...
Popular Post Macktech689 Posted February 6, 2016 Popular Post Share Posted February 6, 2016 You will need to check everything from the screen in the tank to the pump for clogging or damage. LEU chassis are notorious for allowing debris into the tank because of the location of the trash body cleanout. There is a small screen in the pump inlet fitting, usually the spot that will clog up first. Or the pump could be faulty, it costs around $1200 bucks so check all the screens and lines first including the pipes in the tank unit. 4 Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-323311 Share on other sites More sharing options...
Mickey603 Posted February 6, 2016 Author Share Posted February 6, 2016 (edited) OK, Thank You Edited February 6, 2016 by Mickey603 Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-323314 Share on other sites More sharing options...
Macktech689 Posted February 7, 2016 Share Posted February 7, 2016 The picture did not appear when I posted yesterday, not seeing any pump drive percentage. Make sure you're using the SCR start up test correctly before tearing into it. No drive percentage means the pump is not running so no pressure is expected. Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-323389 Share on other sites More sharing options...
Popular Post Mickey603 Posted February 13, 2016 Author Popular Post Share Posted February 13, 2016 Resolved: Changed the pump (was not energizing) & Changed out the Doser Valve (noted the Resistance at 2.3 ohms where it should be 10-15 ohms) Thanks for all the help. P.S. Did check all lines & changed out the line screen. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-324017 Share on other sites More sharing options...
Macktech689 Posted February 13, 2016 Share Posted February 13, 2016 Outstanding, good luck with the truck. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/43919-scr-final-derate/#findComment-324088 Share on other sites More sharing options...
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