DTC P244A or P244B
Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5508882 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 Descriptor DTC P244A Particulate Filter Low Differential Pressure DTC P244B Particulate Filter High Differential Pressure Diagnostic Fault Information
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performanc |
|---|---|---|---|---|
| 5V Reference | P0651 | P2454 | P0651 | P2453 |
| Signal | P2454 | P2454 | P2455 | P2453 |
| Low Reference | — | P2455 | P2454 | P2453 |
Circuit/System Description The exhaust differential pressure sensor measures the pressure difference across the inlet and outlet of the diesel particulate filter. The pressure difference across the diesel particulate filter increases as captured particulates in the diesel particulate filter increases. The engine control module supplies a 5 V reference circuit and a ground on the low reference circuit. The exhaust differential pressure sensor provides a signal voltage to the engine control module, relative to the back pressure as a function of exhaust flow, diesel particulate filter temperature, and diesel particulate filter soot loading. The engine control module converts the signal voltage input to a pressure value. Conditions for Running the DTC DTCs related to the following system/component = Not Set – B17 Barometric Pressure Sensor – B75C Multifunction Intake Air Sensor – B131 Exhaust Temperature Sensor – B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor Engine speed is greater than 1,000 RPM Engine coolant temperature is warmer than −40°C (−40°F) The DTC runs continuously when the above conditions are met. Conditions for Setting the DTC The ECM detects the diesel particulate filter exhaust differential pressure sensor is lower or higher than the minimum threshold. Action Taken When the DTC Sets DTCs P244A and P244B are Type A DTCs Conditions for Clearing the DTC DTCs P244A and P244B are Type A DTCs Diagnostic Aids Certain weather conditions during prolonged drive trips may cause ice to form in the area of the component: B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor If ice is found in the area of the component B154, clean and dry the component and retest to verify the issue has been corrected. Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List Description and Operation Exhaust Aftertreatment System Description 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 Special Tools EN 23738–A Mityvac Circuit/System Verification
- Ignition ON.
- Verify there are no DTCs set related to the following component/system: B17 Barometric Pressure Sensor B75C Multifunction Intake Air Sensor B131 Exhaust Temperature Sensor B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor ⇒ If a related DTC is set Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis. ⇓ If a related DTC is not set
- Ignition ON, verify that the diesel particulate filter (DPF) Differential Pressure parameter is between 0 to +1 kPa (0 to +0.14 PSI) . ⇒ If not within the specified range Refer to Circuit/System Testing. ⇓ If within the specified range
- Engine running, verify that the DPF Differential Pressure parameter is greater than 0 kPa (0 PSI). ⇒ If not greater than 0 kPa (0 PSI) Refer to Circuit/System Testing. ⇓ If greater than 0 kPa (0 PSI)
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed in the Freeze Frame/Failure Records data.
- Verify the DTC is not set. ⇒ If the DTC is set Refer to Circuit/System Testing. ⇓ If no DTC is set
- All OK. Circuit/System Testing
- Verify the following conditions do not exist: Exhaust System — Leaking / Loose / Visible Damage Particulate Filter Differential Pressure Sensor — Hoses / Lines — Kinked / Leaking / Restricted ⇒ If a condition exists Repair as necessary. ⇓ If no condition exists
- Remove and inspect the flexible part of the exhaust differential pressure lines for internal restrictions. ⇒ If any restrictions are found Repair as necessary. ⇓ If no restrictions are found
- Connect the EN 23738–A vacuum gauge to port two (rear of particulate filter) of the B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor.
- Ignition ON, using the EN 23738–A vacuum gauge, slowly apply −10 kPa (3 in Hg) vacuum to the sensor while observing the DPF Differential Pressure parameter.
- Verify the parameter increases smoothly without spikes or dropouts. ⇒ If the parameter does not increase smoothly Replace the B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor. ⇓ If the parameter increases smoothly
- Replace the Diesel Particulate Filter. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Exhaust Pressure Sensor Pipe Replacement - Nitrogen Oxides Catalytic Converter Perform the scan tool Particulate Filter Pressure Sensor Reset after replacing the exhaust pressure differential sensor. Nitrogen Oxides Catalytic Converter with Filter Replacement Perform the scan tool Particulate Filter Reset after replacing the exhaust particulate filter.