Diagnostic Instructions

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

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition 1 Voltage	P0405	P0405	--	P0404, P042E
Solenoid Control	P0402, P0404	P0404	P0404	P0404, P042E
5-Volt Reference	P0405	P0404, P0405	--	--
EGR Position Sensor Signal	P0405	P0405	P0406	P0404, 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%*
EGR Position Sensor Signal	0%	0%	100%*
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:

Conditions for Running the DTC

P0404 and P042E

P0405 and P0406

Conditions for Setting the DTC

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

Conditions for Clearing the DTC

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

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

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 scan tool 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 scan tool EGR position sensor percentage parameter. The reading should be less than 1 percent.
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 EGR valve.
2. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal E 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 A and the ignition 1 voltage circuit terminal E. 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. Test for less than 0.5 volt between the control circuit terminal A and ground.

⇒	If greater than the specified range, 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 5 ohms between the low reference circuit terminal B 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.

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.

6. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal D 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 1 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 C and the 5-volt reference circuit terminal D. Verify the scan tool EGR position sensor parameter is greater than 99 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 of the EGR valve.
2. Test for 6-10 ohms of resistance between the ignition 1 voltage terminal E and the control circuit terminal A.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.