P0406

DTC P0405 or P0406

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 P0405
- Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage

DTC P0406
- Exhaust Gas Recirculation (EGR) Position Sensor Circuit High Voltage

Diagnostic Fault Information






Typical Scan Tool Data






Circuit/System Description

The engine control module (ECM) uses the exhaust gas recirculation (EGR) position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5-volt reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit. If the ECM detects an EGR position sensor voltage that is less than or more than the normal operating range, DTC P0405 or P0406 sets.

Conditions for Running the DTC

* DTCs P0698 and P0699 are not set.
* The ignition is ON.
* This DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P0405

The EGR position sensor voltage is less than 0.26 volt for more than 3 seconds.

P0406

The EGR position sensor voltage is more than 4.75 volt for more than 3 seconds.

Action Taken When the DTC Sets

DTCs P0405 and P0406 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0405 and P0406 are Type B DTCs.

Circuit/System Verification

Important: If you cannot duplicate the condition, operate the vehicle within the conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

1. The EGR Position Sensor parameter is between 0.25-4.75 volts.
2. Engine running, observe the DTC information with a scan tool. DTCs P0405 or P0406 should not set.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame Records data.

Circuit/System Testing

1. Ignition OFF, test for less than 1 ohm of resistance 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.

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

• If less than the specified range, test the 5-volt reference circuit for a short to ground or an 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.

3. Ignition ON, and the EGR valve disconnected, observe that the EGR Position parameter on the scan tool is 0 volt.

• If the EGR Position parameter is more than 0 volt, test the signal circuit for a short to voltage. If the circuits test normal, replace the ECM.

4. Ignition ON and the EGR valve disconnected, connect a jumper wire between the 5-volt reference circuit terminal A of the EGR valve and the signal circuit terminal C of the EGR valve and observe with a scan tool that the EGR sensor parameter displays 4.98-5.02 volts.

• If the EGR Sensor parameter is less than 4.98 volts, test the signal circuit for an open, short to ground, or high resistance. If the circuits test normal, replace the control module.

5. If the circuits, test normal 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 ECM replacement, setup, and programming. Programming and Relearning Verification Tests