Took truck to dealer last Friday because of aftertreatment issues. Dealer updated ECM to try to resolve issue. Finally, he mentioned that he needs 8 hours to diagnose and recommend that I change all 3 sensors which have been replaced last year . Took truck home as is. So I looked up codes 3934 &3911 on quickserve, but the active codes seems to be related to the aftertreatment 1 SCR intermediate NH3 gas sensor power supply, abnormal update rate, data erratic , intermittent or incorrect . Codes 2771 outlet nox sensor abnormal update rate, 3232 inlet nox sensor abnormal update rate also and 4162 DPF Temp sensor voltage below normal or shorted to low source. It seems to me that these are in a closed loop if the NH3 sensor fails which seem to control this circuit it will cause the the other sensors in the aftertreatment to throw fault codes as well because the circuit is broken. Am i missing some information here ? Also do I need to run an update on insite after replacing this NH3 sensor?
Cummins Isx 15, Active Fault codes 3934 & 3911, Inactive codes 4162,3232&2771
Discussion in 'Trucks [ Eighteen Wheelers ]' started by Ironmyke, Sep 20, 2020.
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Please provide engine serial number and current software level in ECM.
Ironmyke and spsauerland Thank this. -
If you look on Quickserve you will see all the modules share the same power supply and also communicate together on the engine private datalink. So a power supply problem will kill them all, or a datalink problem will kill them all. If one module starts to get corrupt it can also take down the datalink. The power supply is provided by the truck, not the engine. Since you did not mention what model or year of truck you have, information you get here will be limited.
spsauerland, Goodysnap and Ironmyke Thank this. -
Last edited: Sep 20, 2020
spsauerland and Goodysnap Thank this. -
Last edited: Sep 20, 2020
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I agree with @Heavyd. The dealer is likely not out of line for requesting the diag time for a wiring beatdown. If the faults are active all the time, standard troubleshooting should indetify the issue in short order. Another story if they are intermittent. I would start with load testing the power supply to the sensor group.
Ironmyke and spsauerland Thank this. -
So I fired her up this morning to take her to the shop from sitting over the weekend, the engine lights are off, all I can think of is that I came up to Baltimore through that storm that rained for 2 consecutive days. I agree with you all I’ll have the shop do a load test on the power supply and check for other issues. Thanks so much to everyone for their knowledgeable inputs.
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