computer problem MX paccar engine

Discussion in 'Peterbilt Forum' started by Rockman1, Sep 14, 2015.

  1. Rockman1

    Rockman1 Bobtail Member

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    Sep 14, 2015
    0
    I own a 2011 Pete with a Paccar motor. Peterbilt can't seem to find the problem. Codes are as following red P3805, P151A, P151E. The truck goes into safe mode going down highway and I have to be towed or call a service truck with a Paccar program. The do a regin and I get home sometimes.
     
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  3. Cat sdp

    Cat sdp . .

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    You should message @Guntoter sounds like what he's dealing with.
     
    Guntoter Thanks this.
  4. Cat sdp

    Cat sdp . .

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    I'm sorry @Rockman1 I'm not up to speed with the mx.........I don't have the info you need.

    Maybe try the diesel garage.com
     
    Last edited: Sep 14, 2015
  5. Guntoter

    Guntoter Road Train Member

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    Phoenix, AZ
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    I don't go into safe mode, and don't de-rate. I have had a complete engine shut down but never "safe mode". I have to stop and do a parked re-gen every 2-3 hours. Sometimes it takes 15 minutes sometimes an hour.
    You need to pull the DPF and see if there is excess soot, and do the same to the EGR, mine had tons in both, had them cleaned. Ran 400 miles, both were plugged again, cleaned them, "re-gen required" after 400 miles again. Everyone at Paccar corporate, and Rush truck center have thrown up their hands... Good luck. Im looking at options, to dump the P.O.S. and take my $30,000 loss and go back to Cummins but this Paccar nightmare has set my business plan back a few years.
     
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  6. pushbroom

    pushbroom Road Train Member

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    3805 is rear nox sensor data too high. Either sensor, def doser, or worst case scr releasing stored def fooling the sensor. The other codes are just derates.
    Is that all you have for codes? Seems like a fairly simple problem for a peterbilt dealer to fix.
     
  7. Belials

    Belials Light Load Member

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    Jun 10, 2014
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    P3805
    Fault code description
    Nox sesnor after catalyst - Data valid but too high, During driving
    Possible causes
    1. Ammonia released during motoring/coasting being read as NOx, this can be caused by:
      • Leaking AdBlue dosing valve.
      • AdBlue deposits/crystallisation releasing ammonia during motoring.
    2. SCR Catalyst releasing excessive stored ammonia, this can be caused by:
      • Incorrect measurement of NOx into catalyst causing excessive dosing.
      • Above normal AdBlue concentration.
      • Poor AdBlue atomisation from the AdBlue dosing valve causing some parts of catalyst to receive more AdBlue than other parts.
      • Exhaust leak before AdBlue dosing valve reducing NOx in catalyst.
    3. Drifted NOx after catalyst sensor.
    Troubleshooting Steps (click to view)
    Technical data

    "NOx sensor after catalyst (F843)"


    Location of component(s)

    "Location Information, EAS-3"


    Electrical diagram(s)

    Refer to the OEM service manual for more information.


    Description of component(s)

    "NOx sensor after catalyst (F843)"


    Block diagram

    "Block Diagram, EAS-3"



    Step-by-step troubleshooting



    Perform the troubleshooting steps below using the breakout harness, if necessary, to check electrical components such as sensors, electrical control units, and harnesses. Back probing is not recommended, as it could damage the harness. The ignition should always be in the OFF position when connecting or disconnecting electrical components to reduce the likelihood of damage to the components.




    ◾Disconnecting the EAS connectors during the troubleshooting process causes multiple errors.


    ◾For specific electrical component information and pin out locations, always refer to the technical data.


    ◾It is necessary to exit the fault code menu in DAVIE and run the diagnostic test again to identify a change in errors.


    ◾Remember that the truck's operational and mechanical issues may be the root cause of both active and inactive fault codes. Refer to the 'possible causes' section.





    Step-by-Step 1: Check Fault Codes



    Step 1A: Check for Fault Codes



    Troubleshooting steps

    1.Turn the key switch ON.


    2.Use DAVIE to check for fault codes.


    Is fault code P3805 active?

    ◾Yes – Proceed to step 1B


    ◾No – Proceed to step 6A



    Step 1B: Check for related fault codes



    Troubleshooting steps

    1.Turn the key switch ON.


    2.Use DAVIE to check for fault codes.


    Is fault code P3808, P3809, P3812, P3962, P3963, P3806, P3818, P3807 or P1711 active?

    ◾Yes – Stop troubleshooting P3805. Refer to the troubleshooting information for these fault codes before continuing with this procedure.


    ◾No – Proceed to step 2A


    Step by step 2: Check the DEF decomposition pipe



    Step 2A: Check for Deposits in the Decomposition Pipe



    Troubleshooting steps

    1.Turn the key switch OFF.


    2.Engine off.


    3.Remove the decomposition pipe from the vehicle.


    4.Inspect for excessive DEF deposits and crystallization.


    Are excessive deposits/crystallization found inside the decomposition pipe?

    ◾Yes – Clean the decomposition pipe - Proceed to step 2B


    ◾No – Proceed to step 2B



    Step 2B: Check for poor DEF spray atomization and distribution



    Troubleshooting steps

    1.Inspect decomposition pipe and SCR inlet pipe for evidence of liquid DEF accumulating and running through exhaust pipe toward the catalyst.


    Is there evidence of liquid DEF accumulating and running in the pipe toward the catalyst?

    ◾Yes – Check dosing valve tip for debris and crystallization. Clean and reinstall dosing valve and reinstall decomposition pipe - Proceed to step 2C


    ◾No – Reinstall decomposition pipe. Proceed to step 2C



    Step 2C: Check for exhaust leakage



    Troubleshooting steps

    1.Inspect all exhaust connections between engine outlet and decomposition pipe inlet for loose/missing clamps and broken pipes.


    Are there loose clamps or broken exhaust pipes?

    ◾Yes – Repair leak - Proceed to step 3A


    ◾No – Proceed to step 3A


    Step by step 3: Check the DEF concentration



    Step 3A: Check DEF Concentration



    Troubleshooting steps

    1.Check the DEF concentration according to the job 'check DEF' in Engine Rapido.


    Is the DEF concentration between 32% and 33%?

    ◾Yes – Proceed to step 3B


    ◾No – Replace DEF - Proceed to step 3B



    Step 3B: Check for crystallization, blockage, exhaust leaks, and incorrect DEF concentration



    Troubleshooting steps

    1.If crystallization, dosing valve blockage, exhaust leaks, or incorrect DEF concentration has been found and corrected, then confirm repair.


    Have crystallization, dosing valve blockage, exhaust leaks, or incorrect DEF concentration been found and corrected?

    ◾Yes – Proceed to step 6A


    ◾No – Proceed to step 4A


    Step by step 4: Check DEF dosing valve



    Step 4A: Check DEF dosing valve accuracy



    Troubleshooting steps

    1.Perform the DEF pump module override test as described in “Explanatory Notes to DAVIE'


    Does the amount of collected DEF meet the specifications displayed by DAVIE?

    ◾Yes – Reinstall DEF dosing valve. Proceed to step 5A


    ◾No – Replace DEF dosing valve. Repeat DEF pump module override test. If the amount is still incorrect then contact the Engine Support Center. Otherwise continue to step 6A.


    Step by step 5: Check the NOx sensor after catalyst



    Step 5A: Check for physical damage



    Troubleshooting steps

    1.Turn the key switch OFF.


    2.Disconnect the NOx after catalyst sensor from the harness.


    3.Inspect the NOx after catalyst sensor harness and connector for:


    ◾Corroded or dirty pins


    ◾Damaged pins


    ◾Pushed back or expanded pins


    ◾Loose connector


    ◾Moisture in or on the connector


    ◾Connector shell damage


    ◾Missing or damaged connector seals


    ◾Wire insulation damage


    4.Remove the NOx after catalyst sensor.


    5.Inspect the NOx after catalyst sensor tip for:


    ◾corrosion


    ◾blockages


    ◾physical damage


    Has any damage been found?

    ◾Yes – Repair damage. Proceed to step 6A to confirm repair. If fault recurs then return to step 5B.


    ◾No – Proceed to step 5B



    Step 5B: Check for sensor contamination



    Troubleshooting steps

    1.This test can be negatively affected by truck exhaust inside the shop. Before beginning this test, the truck must be moved outside or efforts must be made to vent the exhaust outside the shop.


    2.Remove the NOx sensor before catalyst from the exhaust system, leaving it connected to the wiring harness.

    Lubricate the NOx sensor or plug threads with high temperature lubricant to aid in sealing and removal. Install another NOx sensor or other plug into the NOx sensor mounting hole. If using a plug, the mating thread is M20x1.5-6e and the total threaded length must not exceed ¾ inch. Ensure that the removed NOx sensor is not in contact with non-metallic parts as it will become hot during this procedure.


    3.Initiate a stationary regeneration.


    4.Use DAVIE to monitor the NOx sensor before catalyst.


    5.It is normal for any of the following fault codes to be set during this test and they do not indicate a problem. If codes P3971, P3977, P3978 are set they should be cleared before proceeding.


    Is the NOx concentration (NOx PPM) between -20 and 40?

    ◾Yes – Abort the regeneration and reinstall the NOx sensor and proceed to Step 5C. Use caution during installation, the NOx sensor could be hot.


    ◾No – Contact Engine Support Center for further instructions.



    Step 5C: Confirm operation and check accuracy



    Troubleshooting steps

    1.Connect all components.


    2.Move electrical and DEF connections from truck-mounted DEF dosing valve to another DEF dosing valve. Put secondary DEF dosing valve in a bucket to catch dosed DEF. The bucket should be no smaller than 1 gallon.


    3.Perform a stationary regeneration and record an SCR overview. For more information, go to 'Explanatory notes to DAVIE'


    4.Compare the NOx before catalyst sensor value to the NOx after catalyst sensor value shortly before the end of the regeneration. The NOx before catalyst sensor value should be within 40 ppm of the NOx after catalyst sensor value.


    5.It is normal for fault codes P3978 and/or P3977 to be set during this test and they do not indicate a problem. If they are set, they should be cleared before proceeding.


    6.Return the DEF dosing valve connections to their original configuration.


    Shortly before the end of the stationary regeneration is the NOx before catalyst sensor value within 40 ppm of the NOx after catalyst sensor value?

    ◾Yes – Contact the Engine Support Center for further instructions.


    ◾No – Replace the NOx before catalyst sensor. Proceed to step 6A.


    Step-by-Step 6: Clear the Fault Code



    Step 6A: Disable the Fault Code



    Troubleshooting steps

    1.Connect all components.


    2.Drive the truck for 30 minutes at freeway speed.


    3.Check for active faults after completion of the drive.


    Is fault code P3805 inactive?

    ◾Yes – Proceed to step 6B


    ◾No – Return to the last completed troubleshooting steps

    If all the steps have been completed and rechecked, contact the Engine Support Center for further instructions.



    Step 6B: Clear the inactive fault codes



    Troubleshooting steps

    1.Connect all components.


    2.Turn the key switch ON.


    3.Use DAVIE to clear the inactive fault codes.


    Have all the fault codes been cleared?

    ◾Yes – Repair complete


    ◾No – Troubleshoot any remaining active fault codes


    P151A
    Fault code description
    Aftertreatment system - Misuse detection, Level 1
    Possible causes (click to view)
    • Low DEF fluid level
    • P3796
    • P3797
    • P3798
    • P3799
    • P3800
    • P3801
    • P3802
    • P3803
    • P3804
    • P3805
    • P3806
    • P3807
    • P3808
    • P3809
    • P3812
    • P3813
    • P3814
    • P3817
    • P3818
    • P3823
    • P3829
    • P3843
    • P3845
    • P3847
    • P3848
    • P3849
    • P3850
    • P3851
    • P3852
    • P3857
    • P3858
    • P3859
    • P3860
    • P3861
    • P3862
    • P3863
    • P3864
    • P3865
    • P3866
    • P3867
    • P3868
    • P3869
    • P3870
    • P3871
    • P3872
    • P3873
    • P3921
    • P3924
    • P3925
    • P3926
    • P3927
    • P3931
    • P3967
    • P3969
    • P3870
    • P3973
    • P3984

    P151E
    Fault code description
    Aftertreatment system - Misuse detection, Level 4 extended
    Possible causes (click to view)
    • Low DEF fluid level
    • P3796
    • P3797
    • P3798
    • P3799
    • P3800
    • P3801
    • P3802
    • P3803
    • P3804
    • P3805
    • P3806
    • P3807
    • P3808
    • P3809
    • P3812
    • P3813
    • P3814
    • P3817
    • P3818
    • P3823
    • P3829
    • P3843
    • P3845
    • P3847
    • P3848
    • P3849
    • P3850
    • P3851
    • P3852
    • P3857
    • P3858
    • P3859
    • P3860
    • P3861
    • P3862
    • P3863
    • P3864
    • P3865
    • P3866
    • P3867
    • P3868
    • P3869
    • P3870
    • P3871
    • P3872
    • P3873
    • P3921
    • P3924
    • P3925
    • P3926
    • P3927
    • P3931
    • P3967
    • P3969
    • P3870
    • P3973
    • P3984
    P151A
    Fault code description
    Aftertreatment system - Misuse detection, Level 1
    Possible causes (click to view)
    • Low DEF fluid level
    • P3796
    • P3797
    • P3798
    • P3799
    • P3800
    • P3801
    • P3802
    • P3803
    • P3804
    • P3805
    • P3806
    • P3807
    • P3808
    • P3809
    • P3812
    • P3813
    • P3814
    • P3817
    • P3818
    • P3823
    • P3829
    • P3843
    • P3845
    • P3847
    • P3848
    • P3849
    • P3850
    • P3851
    • P3852
    • P3857
    • P3858
    • P3859
    • P3860
    • P3861
    • P3862
    • P3863
    • P3864
    • P3865
    • P3866
    • P3867
    • P3868
    • P3869
    • P3870
    • P3871
    • P3872
    • P3873
    • P3921
    • P3924
    • P3925
    • P3926
    • P3927
    • P3931
    • P3967
    • P3969
    • P3870
    • P3973
    • P3984

    P151E
    Fault code description
    Aftertreatment system - Misuse detection, Level 4 extended
    Possible causes (click to view)
    • Low DEF fluid level
    • P3796
    • P3797
    • P3798
    • P3799
    • P3800
    • P3801
    • P3802
    • P3803
    • P3804
    • P3805
    • P3806
    • P3807
    • P3808
    • P3809
    • P3812
    • P3813
    • P3814
    • P3817
    • P3818
    • P3823
    • P3829
    • P3843
    • P3845
    • P3847
    • P3848
    • P3849
    • P3850
    • P3851
    • P3852
    • P3857
    • P3858
    • P3859
    • P3860
    • P3861
    • P3862
    • P3863
    • P3864
    • P3865
    • P3866
    • P3867
    • P3868
    • P3869
    • P3870
    • P3871
    • P3872
    • P3873
    • P3921
    • P3924
    • P3925
    • P3926
    • P3927
    • P3931
    • P3967
    • P3969
    • P3870
    • P3973
    • P3984

    Hope this helps.
     
  8. joepjack1

    joepjack1 Bobtail Member

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    5
    Sep 19, 2017
    0
    I get the P3805 just from turning the key forward, DEF light flashing,CEL. Haven’t even started the engine yet. Bad sensor??
     
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