For 1990-2009 cars

### 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 P0404 03: Exhaust Gas Recirculation (EGR) Control Circuit Low Voltage
DTC P0404 0B: Exhaust Gas Recirculation (EGR) Control Circuit High Current
DTC P0404 51: Exhaust Gas Recirculation (EGR) Control Circuit Malfunction
DTC P0404 52: Exhaust Gas Recirculation (EGR) Control Circuit Malfunction
DTC P0404 55: Exhaust Gas Recirculation (EGR) Control Circuit Too Few Transitions
DTC P0404 56: Exhaust Gas Recirculation (EGR) Control Circuit Too Many Transitions
DTC P0404 59: Exhaust Gas Recirculation (EGR) Control Circuit Protection Time-Out
DTC P0404 5A: Exhaust Gas Recirculation (EGR) Control Circuit Not Plausible
DTC P0404 5B: Exhaust Gas Recirculation (EGR) Control Circuit Malfunction

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Control | P0404 03, P0489 02, P0489 12 | P0403 04 | P0490 01, P0490 11 | P0404 0B, P0404 51, P0404 52, P0404 52, P0404 5B, P0404 5A, P0404 56, P0404 55, P0404 59
Ground | -- | -- | -- | --

### 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

• | The ignition is ON, or the engine is running.

• | The DTCs run continuously when the above conditions are met.

### 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 DTCs.

### Conditions for Clearing the DTC

DTC P0404 is a Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### 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

### 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 (EGR) Valve.
2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.

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

3. Connect a test lamp between the control circuit terminal 6 and the ground circuit terminal 2.
4. Command the EGR Valve ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. If all circuits test normal, test or replace the Q14 Exhaust Gas Recirculation (EGR) Valve.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Exhaust Gas Recirculation Valve Replacement

• | Vacuum Pump Assembly Replacement

• | Engine Control Module Replacement for ECM replacement, setup, and programming