P2454
DTC P2454 or P2455
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC 2454
- Diesel Particulate Filter Differential Pressure Sensor Circuit Low Voltage
DTC 2455
- Diesel Particulate Filter Differential Pressure Sensor Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The exhaust differential pressure sensor measures the pressure difference across the inlet and outlet of the diesel particulate filter (DPF). The pressure difference across the DPF increases as captured particulates in the DPF increases. A diaphragm within the exhaust differential pressure sensor is displaced by the pressures change that occur from particulate matter loading. The sensor translates this action into electrical resistance. The engine control module (ECM) supplies a 5-volt reference circuit and a ground on the low reference circuit. The exhaust differential pressure sensor provides a signal voltage to the ECM, relative to the back pressure as a function of exhaust flow, DPF temperature, and DPF soot loading. The ECM converts the signal voltage input to a pressure value.
Conditions for Running the DTC
* The engine is running for greater than 4 seconds.
* The ignition 1 voltage is greater than 11 volts.
* The above conditions are met for greater than 2 seconds.
* DTCs P2454 and P2455 run continuously within the above enabling conditions.
Conditions for Setting the DTC
P2454
The ECM detects that the exhaust pressure differential sensor voltage is less than 0.93 volt for 2 seconds.
P2455
The ECM detects that the exhaust pressure differential sensor voltage is greater than 4.1 volts for 2 seconds.
Action Taken When the DTC Sets
DTCs P2454 and P2455 are Type A DTCs.
Conditions for Clearing the DTC
DTCs P2454 and P2455 are Type A DTCs.
Diagnostic Aids
* Inspect the exhaust differential pressure sensor terminals for corrosion.
* Inspect the harness connector terminals for proper tension.
Special Tools
* J 23738-A Mityvac
* J 35555 Metal Mityvac
Circuit/System Verification
1. Verify that DTCs P0652 or P0653 are not set.
^ If the DTCs are set, refer to DTC P0652 or P0653. P0652
2. Verify the integrity of entire DPF system by inspecting for the following conditions:
* Damaged components
* Loose or improper installation
* Leaks or restrictions in the exhaust differential pressure lines or hoses. The pressure lines should have a continuous downward gradient, without sharp bends, or kinks from the pressure sensor to the exhaust filter assembly.
3. Ignition ON, observe the scan tool Particulate Filter Pressure Variance parameter. The value should be between -1.0 kPa to +0.3 kPa.
4. Engine running at idle, observe the scan tool Particulate Filter Pressure Variance parameter. The value should be between 0-3 kPa.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Important: Perform the Repair Verification after completing the Circuit/System Testing.
1. Visually and physically inspect the DPF pressure differential lines for the following conditions:
* A loose fit
* Any cracking
* An internal restriction
* Incorrect routing
^ If a condition is found, repair or replace the differential pressure lines as necessary.
2. Ignition OFF, disconnect the harness connector at the exhaust differential pressure sensor.
3. Ignition OFF for 90 seconds, measure for less than 5 ohms between the low reference circuit terminal 1 and ground.
^ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
^ If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
^ If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
5. Verify the scan tool Particulate Filter Pressure Variance parameter is greater than 98 kPa.
^ If less than the specified range, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM.
6. Install a 3A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the scan tool Particulate Filter Pressure Variance parameter is less than 13 kPa.
^ If greater than the specified range, test the signal circuit terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
7. If all circuits and the exhaust differential pressure sensor lines test normal, test or replace the exhaust differential pressure sensor.
Component Testing
Important: You must perform the Circuit/System Testing in order to verify the integrity of the exhaust pressure differential sensor circuits before proceeding with the Component Testing.
1. Ignition OFF, remove the exhaust differential pressure sensor.
2. Install a 3A fused jumper wire between the 5-volt reference circuit terminal 3 and the corresponding terminal of the exhaust pressure differential sensor.
3. Install a jumper wire between the low reference circuit terminal 1 of the exhaust differential pressure sensor and ground.
4. Install a jumper wire at signal circuit terminal 2 of the exhaust pressure differential sensor.
5. Connect a DMM between the jumper wire from signal circuit terminal 2 of the exhaust differential pressure sensor and ground.
6. Ignition ON, with the J 23738-A or the J 35555, slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 4.8-0.4 volts, without any spikes or dropouts.
^ If the voltage is erratic, replace the exhaust differential pressure sensor.
Repair Instructions
* Exhaust Particulate Filter Cleaning (LMM DPF Service Regeneration) Exhaust Particulate Filter Cleaning (LMM DPF Regeneration Enable)
* Exhaust Pressure Differential Sensor Pipe Replacement
* Exhaust Pressure Differential Sensor Replacement
Repair Verification
Notice: Refer to Diesel Particulate Filter (DPF) Regeneration Enable Notice.
Certain engine control conditions can cause the particulate filter to overload with soot. It will be necessary to clean the particulate filter as instructed to remove the excess soot accumulation. To avoid the customer's return to the service department, perform the Exhaust Particulate Cleaning procedure.