Operation CHARM: Car repair manuals for everyone.
Home >> Chevy Truck >> 2008 >> Silverado 2500 2WD V8-6.6L DSL Turbo >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P244B

P244B



DTC P244B

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 P244B
- Diesel Particulate Filter Differential Pressure Too High

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

As soot loading continues to increase, differential pressure increases. When differential pressure exceeds a calibrated threshold, this diagnostic will run and fail.

Conditions for Running the DTC

* The engine is running.
* DTC P244B runs continuously when the above condition is met.

Conditions for Setting the DTC

* The ECM has determined that the differential pressure across the DPF is greater than a calibrated threshold, based on a calculated exhaust flow rate and the DPF temperature.
* The condition exists for greater than 30 seconds.

Action Taken When the DTC Sets

* DTC P244B is a Type A DTC.
* The ECM commands the engine control system to operate in Reduced Engine Power mode.
* A message center or an indicator may display Reduced Engine Power.
* The DPF regeneration is inhibited.

Conditions for Clearing the MIL/DTC

DTC P244B 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.
* 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.
* 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.
* Not operating the vehicle under the proper conditions to perform a full and effective regeneration OR ignoring the Clean Exhaust Filter message may cause this DTC to set.

Special Tools

* J 23738-A Mityvac
* J 35555 Metal Mityvac

Circuit/System Verification

1. 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

2. Engine running at a warm stabilized idle, observe the scan tool Particulate Filter. Pressure Variance parameter. The value should be between 0-3 kPa.
3. Verify the following scan tool parameters:

* Engine Run Time Since Last DPF Regeneration parameter-The value should be less than 22 hours.
* Fuel Used Since Last DPF Regeneration parameter-The value should be less than 272 liters (71 gallons).
* Distance Since Last DPF Regeneration parameter-The value should be less than 1,030 kilometers (640 miles) at sea level, or less than 772 kilometers (480 miles) when equal to or above 5,000 feet altitude.

^ If any of the parameters are greater than the specified range, perform a DPF Service Regeneration. Refer to Exhaust Particulate Filter Cleaning (LMM DPF Regeneration Enable) Exhaust Particulate Filter Cleaning (LMM DPF Service Regeneration).

4. 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.

* Select Capture Info to store the DTC information with the scan tool.

* This DTC may require reviewing the Freeze Frame/Failure Records carefully for accurate diagnosis.

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

* Modifications
* Damaged components
* Bends or kinks
* Loose or improperly installed components-Ensure the smaller diameter pressure line is connected to the front of the DPF and to the smaller port of the differential pressure sensor.
* Improperly routed differential pressure lines-The exhaust differential pressure line should have a continuous downward gradient from the sensor.

1. Test for water in fuel contamination.
2. 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 and gaskets.

3. Test the air induction system for leaks. Perform the Induction System Smoke Test in Charge Air Cooler Diagnosis (Full System Air Leak Test) Charge Air Cooler Diagnosis (Induction System Smoke Test) Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test).
4. Test the charge air cooler (CAC) for leaks. Perform the Full System Air Leak Test in Charge Air Cooler Diagnosis (Full System Air Leak Test) Charge Air Cooler Diagnosis (Induction System Smoke Test) Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test).
5. Test the fuel system for leaking fuel injectors, high fuel pressures, or high fuel injector flow rates. Refer to Fuel Injector Balance Test with Tech 2. Fuel Injector Balance Test With Tech 2
6. Ignition OFF, disconnect the harness connector at the exhaust differential pressure sensor.
7. 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.

8. Disconnect the harness connector X1 at the ECM.
9. Test for less than 5 ohms on the DPF 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.

10. If all circuits, exhaust system, and engine control system 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.

Important: You must 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. Connect a DMM between terminal 2 of the differential sensor and ground.
4. 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. The voltage should vary and transition smoothly without any spikes or dropouts.

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

Repair Instructions

* Exhaust Particulate Filter Cleaning (LMM DPF Regeneration Enable) Exhaust Particulate Filter Cleaning (LMM DPF Service Regeneration) for Service Regeneration.
* Exhaust Particulate Filter Replacement (6.6L - Pickup) Exhaust Particulate Filter Replacement (6.6L - Cab/Chassis)
* Exhaust Pressure Differential Sensor Pipe Replacement (Pickup) Exhaust Pressure Differential Sensor Pipe Replacement (Cab/Chassis)
* Exhaust Pressure Differential Sensor Replacement (Pickup) Exhaust Pressure Differential Sensor Replacement (Cab/Chassis)

Repair Verification

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

* Verify that no DTCs set after the service regeneration.

^ If DTC P244B sets, replace the exhaust particulate filter and perform the DPF Reset For Replace DPF with a scan tool.

* Certain engine control conditions can cause the DPF to overload with soot. It will be necessary to clean the DPF as instructed to remove the excess soot accumulation. To avoid the customer's return to the service department, perform the appropriate Exhaust Particulate Cleaning procedure that is specified in the provided link.
pro multis · About Operation CHARM