Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

DTC P0403 is a Type B DTC.

DTC P0403 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.

1. Disconnect the EGR valve harness connector and probe the EGR high control circuit with a test lamp connected to ground. Command the EGR valve from 0-10 percent and back to 0 percent. The test lamp should illuminate when commanded to 10 percent.

⇒	If the test lamp remains illuminated when commanded to 0 percent, test the EGR high control circuit for a short to voltage.

⇒	If the test lamp does not illuminate, test the EGR high control circuit for an open, high resistance, or short to ground. If the circuit tests normal, replace the control module.

2. Connect a test lamp between the EGR high control circuit and the EGR low control circuit. Command the EGR valve from 0-10 percent and back to 0 percent. The test lamp should illuminate when commanded to 10 percent.

⇒	If the test lamp illuminates when commanded to 10 percent, replace the EGR valve.

⇒	If the test lamp does not illuminate, test the EGR low control circuit for an open or high resistance.

⇒	If all circuits test OK, replace the control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Exhaust Gas Recirculation Valve Replacement