Diagnostic Instructions

DTC Descriptors

DTC P2454: Diesel Particulate Filter Differential Pressure Sensor Circuit Low Voltage

DTC P2455: Diesel Particulate Filter Differential Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Exhaust Differential Pressure Sensor - 5-Volt Reference	P0117, P0652, P2454	P2453	P2455	P0118, P0653, P2455	P2453
Exhaust Differential Pressure Sensor Signal	P2454	P2453	P2454	P2455	P2453
Exhaust Differential Pressure Sensor Low Reference	--	P2453	P2455	--	P2453

Typical Scan Tool Data

Particulate Filter Pressure Variance

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON, Engine OFF Parameter Normal Range: -1.0 kPa to +0.3 kPa
Exhaust Differential Pressure Sensor - 5-Volt Reference	-14.5 kPa	-14.5 kPa	99.9 kPa
Exhaust Differential Pressure Sensor Signal	-14.5 kPa	99.9 kPa	99.9 kPa
Exhaust Differential Pressure Sensor Low Reference	--	99.9 kPa	--

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

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

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Diesel Particulate Filter (DPF) System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Circuit/System Verification

1. Verify that DTCs P0652 or P0653 are not set.

⇒	If the DTCs are set, refer to DTC P0652 or P0653.

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 a warm stabilized 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 to verify the DTC does not reset. 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--Ensure the smaller diameter pressure line is connected to the front of the DPF, and to the smaller port of the differential pressure sensor.

⇒	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 and scan tool disconnected 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 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. Install a jumper wire between the low reference circuit terminal 1 of the exhaust differential pressure sensor and ground.
3. Connect a DMM between the signal circuit terminal 2 of the exhaust differential pressure sensor and ground.
4. 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 and transition smoothly without any spikes or dropouts.

⇒	If the voltage is erratic, replace the exhaust differential pressure sensor.

Repair Instructions

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 90 seconds.
5. Duplicate the Conditions for Running the DTC and use the freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
6. To avoid the customer's return to the service department, perform the Diesel Particulate Filter (DPF) Regeneration Enable.