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VIN L




DTC P2459

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC P2459
- Diesel Particulate Filter Regeneration Too Often

Circuit/System Description

The particulates in the exhaust gases are collected by the diesel particulate filter (DPF). When the filter becomes saturated with particulates, the particulates are incinerated by a regeneration process. The regeneration process increases the exhaust gas temperature, warming the diesel oxidation catalyst (DOC) first, then warming the DPF. The engine control module (ECM) monitors the system with inputs from two exhaust gas temperature (EGT) sensors 1 and 2 and an exhaust pressure differential sensor.

The ECM will command an active regeneration base on a calculated soot model. The soot model calculations are based on the following information:

* Distance since last DPF regeneration
* Fuel used since last DPF regeneration
* Engine run time since last DPF regeneration
* Exhaust pressure differential sensor values

Conditions for Running the DTC

* DTC P0101, P0401, P0402, P2002, P2229, P2453, P2454, or P2455, are not set.
* The engine is running.
* The Intake Air Temperature is warmer than -7°C (19°F)
* The BARO pressure is greater than 75 kPa (11 psi).
* One active regeneration event has completed.
* DTC P2459 runs continuously when the above condition are met.

Conditions for Setting the DTC

The ECM detects that the actual soot level between completed regenerations is greater than predetermined threshold.

Action Taken When the DTC Sets

DTC P2459 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P2459 is a Type B DTC.

Diagnostic Aids

* A skewed or shifted exhaust pressure differential sensor will cause inaccuracies in the soot model and may cause this DTC to set.
* Exhaust leaks in the exhaust system may cause inaccurate gas temperature sensor or exhaust differential pressure values causing this DTC to set.
* Improperly installed or loose exhaust gas temperature (EGT) sensors will cause inaccuracies in the soot model and cause this DTC to set.
* Low engine compression may cause this DTC to set.
* Water in the fuel system will lower the energy of the fuel which lowers the regeneration temperatures and may cause this DTC to set.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation Reference

Exhaust Aftertreatment System Description (Emission Control Systems)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

* J-23738-A Mityvac
* J-35555 Metal Mityvac

Circuit/System Verification

1. Verify that DTCs P003A, P0047, P0048, P0088, P0101, P0201-P0208, P0234, P0263, P0266, P0269, P0272, P0275, P0278, P0281, P0284, P0299, P02E0, P02E2, P02E3, P02E7-P02E9, P02EB, P0300-P0308, P0401, P0402, P046C, P2032, P2033, P2453, 2454, or P2455 are not set.

• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.

2. Engine idling at operating temperature, observe the scan tool Particulate Filt. Pressure Variance parameter. The value should be between 0-3 kPa.
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. Engine running, verify the scan tool Particulate Filt. Pressure Variance parameter is greater than 0 kPa (0 psi) and increases as engine speed is increased.

• If less than the specified range, and the parameter decreases as engine speed is increased, inspect for incorrect differential pressure line routing.

2. Verify the following conditions do not exist:

* Water in fuel contamination-Refer to Contaminants-in-Fuel Diagnosis (Contaminants-in-Fuel Diagnosis).
* Air induction system leaks-Perform the Induction System Smoke Test in Charge Air Cooler Diagnosis (Induction System Smoke Test) (Charge Air Cooler Diagnosis (Induction System Smoke Test)) Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) (Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)) Charge Air Cooler Diagnosis (Full System Air Leak Test) (Charge Air Cooler Diagnosis (Full System Air Leak Test)).
* Charge air cooler (CAC) leaks-Perform the Full System Air Leak Test and Induction System Smoke Test in Charge Air Cooler Diagnosis (Induction System Smoke Test) (Charge Air Cooler Diagnosis (Induction System Smoke Test)) Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) (Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)) Charge Air Cooler Diagnosis (Full System Air Leak Test) (Charge Air Cooler Diagnosis (Full System Air Leak Test)).
* Exhaust system leaks. An exhaust system leak may cause inaccurate B131 exhaust temperature sensor or B154 exhaust pressure differential sensor values causing this DTC to set.
* Improperly installed or loose B131 exhaust gas temperature (EGT) sensors will cause inaccuracies in the soot model and cause this DTC to set.
* Q57 Indirect fuel injector leaking or restricted-Refer to Indirect Fuel Injector Diagnosis (Indirect Fuel Injector Diagnosis)
* Engine mechanical condition, for example low compression. Refer to Symptoms - Engine Mechanical (Symptoms - Engine Mechanical).

• If a condition is found, repair as necessary.

3. Inspect the B154 exhaust pressure differential sensor system for any of the following conditions:

* Modifications
* Damaged components
* A skewed or shifted B154 exhaust pressure differential sensor. A sensor that is skewed will cause inaccuracies in the soot model and may cause this DTC to set. Refer to Component Testing.
* Loose or improperly installed components-Ensure the smaller diameter pressure line is connected to the rear of the exhaust particulate filter and to the smaller port of the B154 exhaust pressure differential sensor.
* Improperly routed differential pressure lines-The B154 exhaust pressure differential sensor line should have a continuous downward gradient without any sharp bends or kinks from the sensor to the DPF.
* Inspect the flexible part of the B154 exhaust pressure differential sensor lines for internal restrictions.

• If a condition is found, repair as necessary.

4. Ignition ON, observe the scan tool EGR Position Sensor and Desired EGR Position parameters while commanding the EGR solenoid to 20 percent and 0 percent. The values should remain equal to or less than 3 percent.

• If greater than the specified range, replace the Q14 exhaust gas recirculation valve and gaskets.

5. Test the charge air cooler (CAC) for leaks. Perform the Full System Air Leak Test and Induction System Smoke Test in Charge Air Cooler Diagnosis (Induction System Smoke Test) (Charge Air Cooler Diagnosis (Induction System Smoke Test)) Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) (Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)) Charge Air Cooler Diagnosis (Full System Air Leak Test) (Charge Air Cooler Diagnosis (Full System Air Leak Test)).
6. If all components test normal, replace the diesel particulate filter.

Component Testing

1. Ignition OFF, remove the B154 exhaust pressure differential sensor.
2. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the corresponding terminal of the B154 exhaust pressure differential sensor. Install a jumper wire between the low reference circuit terminal 3 of the B154 exhaust pressure differential sensor and ground.
3. Connect a DMM between terminal 2 of the B154 exhaust pressure differential sensor and ground.
4. Ignition ON, with the J-23738-A or J-35555 connected to the B154 exhaust pressure differential sensor rear pressure port, slowly apply vacuum while monitoring the voltage on the DMM. The voltage should vary and transition smoothly without any spikes or dropouts.

• If the voltage is erratic, replace the B154 exhaust pressure differential sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.

* Exhaust Particulate Filter Replacement (LMM) (Service and Repair) Exhaust Particulate Filter Replacement (20 Series) (Service and Repair) Exhaust Particulate Filter Replacement (35 Series) (Service and Repair)
* Exhaust Pressure Differential Sensor Pipe Replacement (Exhaust Pressure Differential Sensor Pipe Replacement)
* Exhaust Pressure Differential Sensor Replacement (Exhaust Pressure Differential Sensor Replacement)
* Perform the following scan tool reset procedures after replacing the SCR/DPF:

1. NOx Catalyst Reductant Loading Reset
2. NOx Catalyst Reset
3. DPF/Catalyst 2 Reset
4. Diesel Particulate Filter (DPF) Service Regeneration (Diesel Particulate Filter (DPF) Service Regeneration)

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