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 Descriptors

DTC P0403: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit
DTC P0404: Exhaust Gas Recirculation (EGR) Open Position Performance
DTC P0405: Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage
DTC P0406: Exhaust Gas Recirculation (EGR) Position Sensor Circuit High Voltage
DTC P042E: Exhaust Gas Recirculation (EGR) Closed Position Performance

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage | * | P0403, P0405 | -- | P0404, P042E
Solenoid Control | P0402 | P0403, P0404 | P0403, P0404 | P0404, P042E
5-Volt Reference | P0107, P0405, P0452, P0651, P2077, P2106 | P0405 | P0107, P0446, P0453, P0651, P2106 | --
EGR Position Sensor Signal | P0405 | P0405 | P0406 | P0404, P042E
Low Reference | -- | P0406 | -- | --
* Engine cranks but does not run and the fuse for the ignition 1 circuit opens.

### Typical Scan Tool Data

#### EGR Position Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: 0-4%
Ignition 1 Voltage | -- | -- | --
Solenoid Control | 99% | -- | --
5-Volt Reference | 0% | 0% | 99%*
EGR Position Sensor Signal | 0% | 0% | 99%*
Low Reference | -- | 0% | --
* Internal ECM damage may occur if the circuit is shorted to B+.

### Circuit Description

Voltage is provided to the exhaust gas recirculation (EGR) valve by the ignition 1 voltage circuit through a fuse. Ground is provided to the EGR valve on the control circuit by a low side driver within the engine control module (ECM). The ECM monitors the voltage on the control circuit of the EGR valve to determine if a failure is present.

The ECM monitors the position of the EGR valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve.

The EGR valve utilizes the following circuits:

• | An ignition 1 voltage circuit

• | A control circuit

• | A 5 volt reference circuit

• | A signal circuit

• | A low reference circuit

### Conditions for Running the DTC

#### P0403, P0404, and P042E

• | DTCs P0112, P0113, P0405, P0406, P0502, P0562, and P0563 are not set.

• | The engine is running.

• | The intake air temperature (IAT) is between 3-80°C (37-176°F).

• | The ignition voltage is between 11-16 volts.

• | The Desired EGR position is greater than 0 percent and does not change greater than 3 percent - DTC P0404 only.

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

#### P0405 and P0406

• | The engine is running.

• | The ignition voltage is between 11-16 volts.

• | The DTC runs continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P0403

The ECM detects an open, short to ground or voltage on the control circuit of the EGR valve.

#### P0404

The ECM detects a difference between the actual EGR position and the commanded EGR position of greater than 15 percent.

#### P0405

The ECM detects that the EGR position sensor percentage is less than 2 percent.

#### P0406

The ECM detects that the EGR position sensor percentage is greater than 98 percent.

#### P042E

The ECM detects the difference between the actual EGR position and the learned EGR position is greater than 10 percent.

### Action Taken When the DTC Sets

• | DTCs P0403, P0405, and P0406 are Type A DTCs.

• | DTCs P0404 and P042E are Type B DTCs.

### Conditions for Clearing the DTC

• | DTCs P0403, P0405, and P0406 are Type A DTCs.

• | DTCs P0404 and P042E are Type B DTCs.

### Diagnostic Aids

• | If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.

• | The scan tool 5-volt reference parameter should display between 4.8-5.2 volts.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exhaust Gas Recirculation (EGR) 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

### Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTC P0651 should not set.

⇒ | If DTC P0651 is set, refer to DTC P0641 or P0651.

2. Ignition ON, observe the scan tool EGR Position Variance parameter while commanding the EGR valve to a 100 percent. The reading should be less than 15 percent.
3. Engine running, observe the scan tool EGR position sensor percentage parameter. The reading should be less than 4 percent.
4. 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 EGR valve.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 5 and ground.

⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

3. Connect a test lamp between the control circuit terminal 1 and the ignition 1 voltage circuit terminal 5. The test lamp should not illuminate.

⇒ | If test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Command the EGR valve to 100 percent with a scan tool. The test lamp should illuminate.

⇒ | If test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. Ignition OFF, test for less than 1 ohm 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 ECM.

6. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 4 and ground.

⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.

⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

7. Verify the scan tool EGR position sensor parameter is less than 3 percent.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

8. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 4. Verify the scan tool EGR position sensor parameter is greater than 95 percent.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

9. If all circuits test normal, test or replace the EGR valve.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the EGR valve.
2. Test for 6-10 ohms between the ignition 1 voltage terminal 5 and control terminal 1.

⇒ | If not within the specified range, replace the EGR valve.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Exhaust Gas Recirculation Valve Replacement

• | Control Module References for engine control module replacement, setup, and programming