For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P2452 03: Diesel Particulate Filter Differential Pressure Sensor Circuit Voltage Below Threshold
DTC P2452 07: Diesel Particulate Filter Differential Pressure Sensor Circuit Voltage Above Threshold
DTC P2454: Diesel Particulate Filter Differential Pressure Sensor Circuit Low Voltage
DTC P2455: Diesel Particulate Filter Differential Pressure Sensor Circuit High Voltage

### Circuit/System Description

The diesel exhaust after-treatment system consists of an under hood pre-catalytic converter and an underbody catalytic converter. The underbody catalytic converter also consists of the main Diesel Oxidation Catalyst (DOC) and the coated Diesel Particulate Filter (DPF). One of the main purposes of the DPF is to collect particulates from the engine exhaust in order to minimize discharge of soot to the atmosphere. The soot particles accumulate in the channels of the DPF and are burned off at regular intervals through a process called regeneration. This prevents the DPF from clogging. The ECM commands the DPF regeneration after calculating various vehicle conditions such as DPF pressure difference, exhaust gas temperature, engine oil quality, engine speed, etc. Excessive accumulation of the soot in the DPF can cause a drop in the engine performance. During regeneration, additional fuel is injected via multiple post injections in order to increase the exhaust gas temperature. During this period, the DPF temperature is raised to approximately 600°C and the accumulated soot is oxidized or burned off into carbon dioxide (CO2).

### Conditions for Running the DTC

• | The ignition is ON, or the engine is running.

• | The DTCs run continuously when the above condition is met.

### Conditions for Setting the DTC

#### P2452 03, P2454

The ECM detects the DPF differential pressure sensor signal is less than 16 mV for greater than 2 seconds.

#### P2452 07, P2455

The ECM detects the DPF differential pressure sensor signal is greater than 4.9 volts for greater than 1 second.

### Action Taken When the DTC Sets

DTCs P2452, P2454, and P2455 are type A DTCs.

### Conditions for Clearing the DTC

DTCs P2452, P2454, and P2455 are type A DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Ignition ON, observe the scan tool DPF pressure sensor parameter. The parameter should be within 0.45-0.55 volts.
2. Engine idling, observe the scan tool diesel particulate filter data parameter. The reading should be within 0-10 kPa (0-1.5 psi).
3. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Circuit/System Testing

1. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the DPF differential pressure sensor.
2. Test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

3. Install the MAIN fuse. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.

⇒ | If less than the specified range, test the circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒ | If greater than the specified range, test the circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

4. Verify that the scan tool DPF differential pressure sensor parameter is greater than 4.8 volts.

⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.

5. Install a 1A fused jumper wire between the signal circuit terminal 3 and ground. Verify that the scan tool DPF differential pressure sensor parameter is less than 0.5 volts.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.

6. If all circuits/connections test normal, replace the DPF differential pressure sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Exhaust Pressure Sensor Replacement

• | Exhaust Particulate Filter Replacement

• | Control Module References for ECM replacement, programming and setup.