3936/ FMI 18 DIESEL PARTICULATE FILTER (DPF) PRESSURE OUT OF RANGE LOW

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Description This Fault Code Sets when the Diesel Oxidation Catalyst (DOC) Inlet Pressure and Diesel Particulate Filter (DPF) Outlet Pressure delta is Below Normal Operating Range for More than 10 Seconds
Monitored Parameter DOC Inlet Pressure Sensor and DPF Outlet Pressure Sensor
Typical Enabling Conditions Always On
Monitor Sequence None
Execution Frequency Continuous When Enabling Conditions Met
Typical Duration Two Seconds
Dash Lamps MIL, CEL, SEL
Engine Reaction Derate 25%
Verification Run Engine Between 1200 to 1800 rpm With a Load Less Than 10%

 

    1. Visually inspect entire exhaust system for signs of leaks or damage. Are there any leaking or damaged exhaust components?
        1. Yes; repair as necessary.

      1. No; Go to step 2.

    1. Connect DiagnosticLink® .

    1. Using the Selective Catalytic Reduction (SCR) voltage service routine, monitor the Diesel Oxidation Catalyst (DOC) inlet pressure (pin 87) and DPF outlet pressure (pin 72) voltages with the key ON, engine OFF.

    1. Are the DOC inlet and DPF outlet pressure sensors voltages between .44 to .56 volts?
        1. Yes; Go to step 6.

      1. No; Go to step 5.

    1. Inspect electrical connections between suspect sensor connector and Aftertreatment Control Module (ACM) for bent, spread, or corroded pins. Is there any damage found?
        1. Yes; repair as necessary.

      1. No; replace the sensor with the voltage reading outside of the 0.44-0.56 volts.
    1. Inspect the DOC and DPF pressure sensor tubes and elbows for leaks, kinks, or blockages. Were any leaks, kinks or blockages found?
        1. Yes; repair as necessary.

      1. No; Go to step 7.

 

    1. Start the engine and run a Parked Regen. During the last 10% of the parked regen period, is the Selective Catalyst Reduction (SCR) inlet temperature more than 38°C (68.4°F) lower than SCR outlet temperature?
        1. Yes; Go to step 8.

      1. No; Go to step 9.

    1. Perform a low temperature Aftertreatment Device (ATD) check using DiagnosticLink to check for a drifted temperature sensor.  Are the SCR inlet and SCR outlet temperatures within 25°C (45°F) during the last five minutes of this test?
        1. Yes; replace the DOC/SCR module. This indicates an internal failure of the DOC/SCR module.

      1. No; replace the drifted SCR temperature sensor. Go to step 9.

  1. During the parked regen, does either the DOC inlet pressure or DPF outlet pressure sensor drop to 0.0 psi?
      1. Yes; replace the failed sensor.

    1. No; clear fault and release unit. The code likely occurred after extended idle and soot buildup has cleared.

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