P2459

DTC P2459

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 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, they 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 differential pressure 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 differential pressure sensor values

If the ECM detects that the average time between commanded regenerations is less than a calibrated threshold this diagnostic will fail.

Conditions for Running the DTC

* The engine is running.
* One active regeneration event has completed.
* DTC P2459 runs continuously when the above condition is met.

Conditions for Setting the DTC

The ECM detects that the average time between completed regenerations is less than 1 hour 10 minutes.

Action Taken When the DTC Sets

DTC P2459 is a Type A DTC.

Conditions for Clearing the MIL/DTC

DTC P2459 is a Type A DTC.

Diagnostic Aids

* A skewed or shifted exhaust differential pressure 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 1 and 2 will cause inaccuracies in the soot model and cause this DTC to set.
* Low engine compression may cause this DTC to set.
* Corroded fuel injectors will have an inability to properly control regeneration temperatures and may cause this DTC to set.
* Water in the fuel system will lower the energy of the fuel. Emulsified fuel will lower regeneration temperatures that may cause this DTC to set.

Special Tools

* J 23738-A Mityvac
* J 35555 Metal Mityvac

Circuit/System Verification

Verify that DTCs P003A, P0047, P0048, P0087, P0101, P0201-P0208, P02A1, P02A5, P02A9, P02AD, P02B1, P02B5, P02B9, P02E0, P02E7-P02E9, P029D, P0234, P0299, P0300-P0308, P0401, P0402, P046C, P0545, P0546, P0698, P0699, P2032, P2033, P2269, P2453, or P2563 are not set.

If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions

Circuit/System Testing

Important: Perform the Repair Verification after completing the Circuit/System Testing.

1. Visually inspect the exhaust differential pressure system for any of the following conditions:

* Modifications
* Damaged components
* Loose or improperly installed components
* Improperly routed differential pressure lines-The exhaust differential pressure line should have a continuous downward gradient without any sharp bends or kinks from the sensor to the DPF.

2. Remove and visually inspect the flexible part of the exhaust differential pressure lines for internal restrictions.

^ If a condition is found, replace the exhaust differential pressure lines.

3. Test for water in fuel contamination.
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 EGR valve.

5. Test the EGR valve gaskets and cooler gaskets for leaks. Apply a soap solution to the gaskets while commanding the TC Vane Pos. Ctrl. Solenoid ON, and inspect for excessive air bubbles at the EGR valve gaskets and cooler gaskets.

^ If an air leak is found, replace the EGR valve gaskets or EGR cooler gasket.

6. Test the charge air cooler (CAC) for leaks.
7. Test the fuel system for leaking fuel injectors, high fuel pressures, or high fuel injector flow rates.
8. Ignition OFF, disconnect the harness connector at the exhaust differential pressure sensor.
9. Ignition OFF for 90 seconds, test 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.

10. Disconnect the harness connector X1 at the ECM.
11. Test for less than 5 ohms on the differential pressure sensor circuits between the following terminals:

* ECM X1 5-volt reference circuit terminal 14 to exhaust differential pressure sensor terminal 3.
* ECM X1 signal circuit terminal 43 to exhaust differential pressure sensor terminal 2.

^ If greater than the specified range, repair the affected circuit for an open/high resistance.

12. If all circuits and engine control components 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 differential pressure sensor circuits before proceeding with Component Testing.

* Perform the Repair Verification after completing the Component Testing.

1. Ignition OFF, remove the exhaust pressure differential pressure sensor.
2. Install a 3A fused jumper wire between the 5-volt reference circuit terminal 3 and the corresponding terminal of the differential sensor. Install a jumper wire between the low reference terminal 1 of the sensor and ground.
3. Install a jumper wire between the low reference circuit terminal 1 of the differential sensor and ground.
4. Install a jumper wire at terminal 2 of the differential sensor.
5. Connect a DMM between the jumper wire from terminal 2 of the differential sensor and ground.
6. Ignition ON, with the J 23738-A or J 35555 connected to the pressure sensor rear pressure port, slowly apply vacuum to the sensor while monitoring the voltage between the signal terminal 2 and the low reference terminal 1. The voltage should vary between 4.8-0.4 volts without any spikes or dropouts.

^ If the voltage is erratic, replace the differential pressure sensor.

Repair Instructions

* Exhaust Particulate Filter Cleaning (LMM DPF Service Regeneration) Exhaust Particulate Filter Cleaning (LMM DPF Regeneration Enable) for Regeneration Enable.
* Exhaust Particulate Filter Replacement (6.6L (LMM))
* Exhaust Pressure Differential Sensor Replacement

Repair Verification

Notice: Refer to Diesel Particulate Filter (DPF) Regeneration Enable Notice.

Certain engine control conditions can cause the exhaust particulate filter (EPF) to overload with soot. It will be necessary to clean the EPF as instructed to remove the excess soot accumulation. To avoid the customer's return to the service department, perform the Exhaust Particulate Cleaning procedure.