P244B–DIESEL PARTICULATE FILTER DIFFERENTIAL PRESSURE TOO HIGH

For a complete wiring diagram Refer to Section 8W

Theory of Operation

The Diesel particulate filter is an inline canister filter located in the exhaust system between the engine and the muffler. This filter captures and stores ash particles created by the diesel combustion process. This filter is monitored by the ECM with a Differential Pressure Sensor. This sensor measures the difference in exhaust system pressure before and after the particulate filter through tube connections directly to the exhaust pipe. As ash and soot accumulate in the filter, the exhaust pressure at the inlet side of the filter increases as compared to the pressure at the outlet side of the filter.

When Monitored:
With the engine running.
Set Condition:
The ECM detects pressure at the particulate filter above 950 hpa for 10.0 seconds.

Possible Causes

DAMAGED EXHAUST SYSTEM

LEAKING EXHAUST SYSTEM

HIGH RESISTANCE IN EXHAUST DIFFERENTIAL PRESSURE SENSOR CIRCUITS

HOSE/TUBE CONNECTIONS TO THE EXHAUST DIFFERENTIAL PRESSURE SENSOR

EXHAUST DIFFERENTIAL PRESSURE SENSOR

DIESEL PARTICULATE FILTER

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Diagnostic Test

1. CHECKING FOR OTHER DTC'S

NOTE: This DTC indicates that the soot level in the Diesel Particulate Filter is too high. This occurs normally on high mileage vehicles. However, if there is an EGR system problem, turbocharger problem or oil consumption problem with the engine, this DTC can occur on a low mileage vehicle

Turn the ignition on.
With the scan tool, read the ECM DTC's.

Are there other DTC's set in the ECM?

Yes

Repair other DTC's before continuing with this test.

Perform ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Go To 2

2. VISUAL INSPECTION

Turn the ignition off.
Visually inspect the Exhaust Differential Pressure Sensor for physical damage, proper electrical connection and proper mechanical connection. Ensure any tubes and/or hoses connected to the sensor are in good working condition, clear of any restrictions and properly connected at all ends.
Visually inspect the entire exhaust system for bent, crushed or otherwise damaged tubes which may cause an exhaust system restriction.
Inspect the exhaust system for exhaust leaks.

Were any problems found?

Yes

Repair or replace as necessary.

Go To 3

3. PARTICULATE FILTER REGENERATION

Start and idle the engine.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
With the scan tool, perform the Diesel Particulate Filter Regeneration procedure.
After this procedure is complete, turn the ignition off for 60 seconds.
Test drive the vehicle.
With the scan tool, Read DTCs in the Engine Control Module (ECM).

Is the status Active for this DTC?

Yes

Go To 4

Test complete.

4. EXHAUST DIFFERENTIAL PRESSURE SENSOR CIRCUIT HIGH RESISTANCE

Turn the ignition off.
Disconnect the Exhaust Differential Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of each Exhaust Differential Pressure Sensor circuit between the Exhaust Differential Pressure Sensor harness connector and the ECM harness connector.

Is the resistance below 10.0 ohms for each circuit?

Yes

Replace the Diesel Particulate Filter. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Repair the circuit(s) that measured above 10.0 ohms for high resistance. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)