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Aftertreatment Particulate Filter Differential Pressure Sensor Circuit – Voltage Below Normal, or Shorted to Low Source
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Overview
| CODE | REASON | EFFECT |
| Fault Code: 1881 PID: S324 SPN: 3251 FMI: 4/4 LAMP: Amber SRT: |
Aftertreatment Particulate Filter Differential Pressure Sensor Circuit – Voltage Below Normal, or Shorted to Low Source. Low signal voltage or open circuit detected at the aftertreatment differential pressure sensor circuit. |
Active aftertreatment diesel particulate filter regeneration will be disabled. |
 ISX and ISM – Aftertreatment Differential Pressure
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Circuit Description
The electronic control module (ECM) provides a 5 volt supply to the aftertreatment diesel particulate filter differential pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The aftertreatment diesel particulate filter differential pressure sensor provides a signal to the ECM on the aftertreatment diesel particulate filter differential pressure sensor signal circuit. This sensor signal voltage changes based on the differential pressure across the aftertreatment diesel particulate filter.
Component Location
The aftertreatment diesel particulate filter differential pressure sensor is located in the aftertreatment system. Refer to the OEM troubleshooting and repair manual for exact location of the aftertreatment system.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.
Conditions for Setting the Fault Codes
The ECM detects that the aftertreatment diesel particulate filter differential pressure signal voltage is less than 0.25-VDC for more than 1 second.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
- A default value of the aftertreatment diesel particulate filter differential pressure is used.
- Active aftertreatment diesel particulate filter regeneration will be disabled.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
Shop Talk
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.
Possible causes of this fault code include:
- Signal circuit open or shorted to ground in the engine harness or sensor.
- Supply line open or shorted to ground.
Refer to Troubleshooting Fault Code t05-1881
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