Vauxhall Workshop Service and Repair Manuals

DTC P0404

Diagnostic Instructions

DTC Descriptors

Diagnostic Fault Information

Circuit/System Description

The exhaust gas recirculation (EGR) valve is controlled by the engine control module (ECM) through the EGR solenoid. A reference voltage is supplied to the EGR valve solenoid. The ECM controls the solenoid by grounding the control circuit.

Conditions for Running the DTC

Conditions for Setting the DTC

P0404 03

The voltage is below the calibrated value.

P0404 0B

The ECM detects a high current on the output power stage.

P0404 51, P0404 52, P0404 5A or P0404 5B

The ECM detects a positive or negative deviation of the EGR valve.

P0404 55

The ECM detects a permanent negative governor deviation.

P0404 56

The ECM detects a permanent positive governor deviation.

P0404 59

The ECM detects a short circuit over load error.

Action Taken When the DTC Sets

DTC P0404 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0404 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that no other DTCs are set.

⇒	If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. DTCs P0403, P0489 or P0490 should not set.
3. 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

1. Ignition OFF, disconnect the harness connector at the Q14 Exhaust Gas Recirculation Valve and K20 Engine Control Module.
2. Test for greater than 500 kΩ between the low reference circuit terminal 2 and ground.

⇒	If less than the specified range, test the low reference circuit for a short to ground.

3. Test for less than 5 Ω between the low reference circuit terminal 2 at the Q14 Exhaust Gas Recirculation Valve and the low reference circuit terminal listed below at the K20 Engine Control Module.

•	LBS Terminal 49 X1

•	LBY Terminal 95 X1

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance.

4. Connect the harness connector X1 to the K20 Engine Control Module.
5. Ignition ON, test for greater than 11 V between the control circuit terminal 6 and ground.

⇒	If less than the specified range, test the control circuit for a short to ground or an open/high resistance.

6. If all circuits test normal, test or replace the Q14 Exhaust Gas Recirculation Valve.
7. Connect the harness connector to the Q14 Exhaust Gas Recirculation Valve. Clear the DTC information and operate the vehicle within the conditions for running the DTC.

⇒	If the DTC resets, replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.