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 provide an overview of each diagnostic category.

### DTC Descriptors

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
DTC P1404: 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 | P0405 | P0405 | -- | P0404, P1404, P042E
Solenoid Control | P0402, P0404 | P0404 | P0404 | P0404, P1404, P042E
5-Volt Reference | P0405 | P0404, P0405 | -- | --
EGR Position Sensor Signal | P0405 | P0405 | P0406 | P0404, P1404, P042E
Low Reference | -- | P0406 | -- | --

### 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: 0-3%
Ignition 1 Voltage | -- | -- | --
Solenoid Control | 100% | -- | --
5-Volt Reference | 0% | 0% | 100%¹
EGR Position Sensor Signal | 0% | 0% | 100%¹
Low Reference | -- | 0% | --
¹ Internal engine control module (ECM) damage may occur if the circuit is shorted to B+.

### Circuit/System 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

#### P0404, P1404, and P042E

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

• | The engine is running.

• | The intake air temperature (IAT) is greater than 3°C (37°F).

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

#### P0405 and P0406

• | The engine is running.

• | The ignition voltage is between 11.7-16 volts.

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

### Conditions for Setting the DTC

#### P0404

The ECM detects a difference between the actual EGR position and the commanded EGR position of more 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.

#### P1404 or P042E

The ECM detects the difference between the actual EGR position and the learned EGR position is greater than 6.3 percent for Euro III Emissions or 10 percent for Euro IV Emissions.

### Action Taken When the DTC Sets

DTC P0404, P0405, P0406, P042E, and P1404 are Type B DTCs.

### Action Taken When the DTC Sets

DTC P0404, P0405, P0406, P042E, and P1404 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Ignition ON, observe the EGR Position Variance parameter while commanding the EGR valve to a 100 percent. The reading should be less than 15 percent.
2. Engine running, observe the EGR position sensor percentage parameter. The reading should be less than 1 percent.
3. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the EGR valve.

Important: The test lamp is used to load the circuit and may not illuminate.

2. Connect a test lamp between the ignition 1 voltage circuit of the EGR valve and ground.
3. Ignition ON, load test for battery voltage between the ignition 1 voltage circuit of the EGR valve and ground.

⇒ | If less than B+, repair the ignition 1 voltage circuit of the EGR valve for a short to ground or an open/high resistance.

4. Ignition OFF, connect a test lamp between the control circuit of the EGR valve and B+.

⇒ | If test lamp illuminates, test the control circuit of the EGR valve for a short to ground. If the circuit/connections test normal, replace the ECM.

5. Ignition ON, with a scan tool, command the EGR valve to 100 percent and test for less than 0.5 volt between the control circuit of the EGR valve and ground.

⇒ | If greater than 0.5 volt, test the control circuit of the EGR valve for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.

6. Ignition ON, verify that the EGR position sensor parameter is less than 1 percent.

⇒ | If greater than 1 percent, test the signal circuit of the EGR position sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

7. Ignition ON, connect a test lamp between the 5-volt reference circuit of the EGR position sensor and ground.

Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.

8. Test for 4.8-5.2 volts between the 5-volt reference circuit of the EGR position sensor and ground.

⇒ | If less than 4.8 volts, test the 5-volt reference circuit of the EGR position sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒ | If greater than 5.2 volts, test the 5-volt reference circuit of the EGR position sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

9. Ignition ON, test for less than 0.2 volt between the low reference circuit of the EGR position sensor and ground.

⇒ | If greater than 0.2 volt, test the low reference circuit of the EGR position sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

10. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the EGR position sensor and ground.

⇒ | If greater than 5 ohms, test the low reference circuit of the EGR position sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM.

11. Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the EGR position sensor to verify that the EGR position sensor parameter is greater than 99 percent.

⇒ | If less than 99 percent, test the signal circuit of the EGR position sensor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

12. If all circuits/connections test normal, test or replace the EGR valve.

### Component Testing

1. Ignition OFF, disconnect the harness connector of the EGR valve.
2. Measure for 6-10 ohms of resistance between the ignition 1 voltage and control circuit terminal of the EGR valve.

⇒ | If the resistance is out of 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