Captiva

DTC P2453-P2455 - LNP or LNQ

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. A diaphragm within the exhaust differential pressure sensor is displaced by the pressures change that occur from particulate matter loading. The sensor translates this action into electrical resistance. 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.

P2453

P2454

P2455

P2453

P2454

The ECM detects that the exhaust pressure differential sensor voltage is less than 0.83 V for 3 s.

P2455

The ECM detects that the exhaust pressure differential sensor voltage is greater than 4.5 V for 3 s.

DTCs P2453, P2454, and P2455 are Type A DTCs.

DTCs P2453, P2454, and P2455 are Type A DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exhaust Particulate Filter System Description

Electrical Information Reference

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

For equivalent regional tools, refer to Special Tools .

1. Verify that DTCs P0641, or P0651 are not set.

⇒	If any of the DTCs are set, refer to Control Module References .

2. Ignition ON, engine OFF, observe the scan tool DPF Differential Pressure parameter. The value should be between -1.0 to +0.5 kPa (-0.14 to +0.07 PSI).
3. Engine running at a warm stabilised idle, observe the scan tool DPF Differential Pressure parameter. The reading should be between 0.0-3.0 kPa (0.0-0.43 PSI)
4. Engine running at a warm stabilised idle, observe the scan tool DPF Differential Pressure parameter. Increase the engine speed to 3 000 RPM. The value should increase.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

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

1. Verify the integrity of the DPF system by visually and physically inspecting any of the following conditions:

•	Any damaged exhaust system components

•	Loose or improperly installed exhaust system 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.

•	Restrictions in the exhaust differential pressure sensor ports.

•	Damaged, bent, restricted, or kinked exhaust differential pressure lines. The lines should not be changed and should have a continuous downward gradient from the sensor.

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

⇒	If a condition is found replace the exhaust pressure lines.

3. Engine running, verify that the scan tool DPF Differential Pressure 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.

4. Ignition OFF, disconnect the harness connector at the B136 Exhaust Pressure Differential Sensor.
5. Ignition OFF and scan tool disconnected for 90 s, test for less than 5 Ω between the low reference circuit terminal 2 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 K20 Engine Control Module.

6. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.

⇒	If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

⇒	If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

7. Verify the scan tool DPF Differential Pressure parameter is between 4.8-5.2 V.

⇒	If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

8. Install a bridging wire between the low reference circuit terminal 2 and signal circuit terminal 3. Verify the scan tool DPF Differential Pressure parameter is less than 0.5 V.

⇒	If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

9. Ignition OFF for 90 s, disconnect the X1 harness connector at the K20 Engine Control Module.
10. Test for less than 5 Ω between the B136 Exhaust Pressure Differential Sensor 5 V reference circuit terminal 1 and the K20 Engine Control Module 5 V reference circuit terminal 66 X1.

⇒	If greater than the specified range, test the 5 V reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

11. Test for less than 5 Ω between the B136 Exhaust Pressure Differential Sensor signal circuit terminal 3 and the K20 Engine Control Module signal circuit terminal 8 X1.

⇒	If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

12. If all DPF circuits, and the differential pressure lines test normal, test or replace the B136 Exhaust Pressure Differential Sensor.

Note: You must perform the Circuit/System Testing in order to verify the integrity of the exhaust pressure differential sensor circuits before proceeding with the Component Testing.

Static Test

1. Ignition OFF, remove the B136 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 B136 Exhaust Pressure Differential Sensor. Install a jumper wire between the low reference circuit terminal 2 of the B136 Exhaust Pressure Differential Sensor and ground.
3. Connect a DMM between the signal circuit terminal 3 and ground.
4. Ignition ON, with the EN 23738-A Mityvac, slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary and transition smoothly without any spikes or dropouts.

⇒	If the voltage is erratic, replace the B136 Exhaust Pressure Differential Sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.