P0403

DTC P0403 or P046C

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 P046C
- Exhaust Gas Recirculation (EGR) Position Sensor Performance

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. The ECM compares the actual EGR position with the desired EGR position when the EGR valve is commanded open or closed.

The EGR valve is controlled by the ECM through the EGR motor high control and the EGR motor low control circuits. The ECM supplies voltage that is near ignition voltage to the high and low control circuits at all times. The ECM will pulse width modulation (PWM) the low control circuit to ground when EGR is desired. The lower the pulse width, the more the valve will open. The ECM will PWM the high control circuit to ground when the EGR valve is desired closed.

Conditions for Running the DTC

P0403
* The engine is running for more than 0.5 second.
* The EGR duty cycle is more than 10 percent.
* DTC P0403 runs continuously when the above conditions are met.

P046C
* DTCs P0401, P0402, P0403, P0642, or P0643 are not set.
* The EGR valve is actively being controlled.
* DTC P046C runs continuously when the above conditions have been met.

Conditions for Setting the DTC

P0403
* The ECM detects an electrical malfunction on an EGR motor control circuit.
* The above condition is present for more than 30 seconds.

P046C
* The difference between the actual EGR position and the desired EGR position is more than 3 percent.
* The above condition is present for more than 5 seconds.

Action Taken When the DTC Sets

DTCs P0403 and P046C are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0403 and P046C are Type B DTCs.

Special Tools

EN-48565 EGR Test Harness

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. Command the EGR valve to 30 percent with a scan tool. The commanded EGR position and the Actual EGR position should match.
2. Engine running, observe the DTC information with a scan tool. DTCs P0403 or P046C 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

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Turn OFF the ignition. Disconnect the EGR valve. Install the EN-48565 between the EGR valve and the harness connector.
2. Turn ON the ignition. Command the EGR valve to 40 percent and back to 0 percent. The EGR test harness lamp should turn ON between 10 percent and 40 percent, and turn OFF at 0 percent.

^ If the lamp does not turn ON and OFF, test both motor control circuits for an open/high resistance, short to voltage, or short to ground. If the circuits test normal, replace the ECM.
^ If the lamp turns ON and OFF, replace the EGR valve.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests

* Exhaust Gas Recirculation Valve Replacement