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 P2002: Diesel Particulate Filter (DPF) Low Efficiency

### 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 engine is running.

• | The DTC runs continuously when the above condition is met.

### Conditions for Setting the DTC

The ECM detects that the pressure difference of the DPF is less than 0.9 kPa (0.13 psi).

### Action Taken When the DTC Sets

DTC P2002 is a type B DTC.

### Conditions for Clearing the DTC

DTC P2002 is a type B DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component 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

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that no other DTCs are set.

⇒ | If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. Engine idling, observe the scan tool DPF differential pressure parameter. The reading should be within 0-10 kPa (0-1.5 psi).
3. 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

1. Ignition OFF, inspect the hose/pipes to the B154 DPF pressure sensor for leaks, or restrictions.

⇒ | If a condition is found, repair as necessary.

2. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the B154 DPF sensor.
3. Test for less than 5 Ω between the low reference circuit terminal 2 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 K20 ECM.

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

⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K20 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 K20 ECM.

5. Verify the scan tool DPF differential pressure sensor voltage parameter is greater than 4.8 V.

⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the ground circuit terminal 2. Verify the DPF differential pressure sensor voltage parameter is less than 0.5 V.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

7. Ignition OFF, connect the harness connector at the B154 DPF pressure sensor.
8. Ignition ON, observe the scan tool DPF differential pressure sensor voltage parameter. The scan tool should display within 0.45-0.55 V.

⇒ | If not within the specified range, replace the B154 DPF sensor.

9. If all circuit tests normal, replace the DPF.

### 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.