Diagnostic Instructions

DTC Descriptors

DTC P0403: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit

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
5-Volt Reference	P0107, P0452, P0641	P0405	P0641	--
Sensor Signal	P0405	P0405	P0406	P0404, P042E
Low Reference	--	P0406	--	--
EGR Solenoid High Control	--	P0403	P0403	--
EGR Solenoid Low Control	--	P0403	--	--

Circuit Description

The powertrain control module (PCM) tests the exhaust gas recirculation (EGR) system during deceleration. The PCM 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 PCM will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the PCM 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 PCM. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the PCM to determine the EGR valve position. The PCM compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The PCM 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 PCM through the EGR solenoid low control circuit.

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

Conditions for Running the DTC

P0403, P0404, P0405, P0406, P042E

P0404

P0406

The EGR valve is not being commanded with a scan tool.

P042E

Conditions for Setting the DTC

P0403

The PCM detects an electrical malfunction in the EGR solenoid high control circuit or the EGR solenoid low control circuit for more than 20 seconds.

P0404

The difference between the EGR position sensor and the desired EGR position is more than 20 percent for more than 80 seconds.

P0405

The EGR position sensor is less than 4 percent of the 5-volt reference or 0.25 volts for longer than 55 seconds.

P0406

The EGR position sensor voltage is more than 94.7 percent of the 5-volt reference voltage or 4.735 volts for longer than 20 seconds.

P042E

Action Taken When the DTC Sets

Conditions for Clearing the MIL/DTC

DTC P0403, P0404, P0405, P0406, and P042E are Type B DTCs.

Diagnostic Aids

Inspect for excessive deposits on the EGR valve pintle or seat. Remove the EGR valve and inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electronic Ignition (EI) 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

Important: If DTC P0641 or P0651 are also set, diagnose those DTCs first.

1. With the ignition ON and the engine OFF, command the EGR from 0-90 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter through the entire range.
2. 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

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

1. Ignition OFF, disconnect the EGR valve harness connector.
2. Ignition ON, connect a test lamp between B+ and the EGR low control circuit terminal A. The test lamp should illuminate.

⇒	If the test lamp does not illuminate, test the EGR low control circuit for an open/high resistance. If the circuit tests normal, replace the PCM.

3. Connect a test lamp between the EGR high control circuit terminal E and ground. Command the EGR valve from 0-90 percent and exit the EGR Solenoid Output Control. The test lamp should turn ON when commanded between 10 and 90 percent and turn OFF when exiting the EGR Solenoid Output Control.

⇒	If the test lamp is ON after exiting the EGR Solenoid Output Control, test the EGR high control circuit for a short to voltage. If the circuit tests normal, replace the PCM.

⇒	If the test lamp is always OFF while commanding the EGR valve from 0-90 percent, test the EGR high control circuit for an open, high resistance, or a short to ground. If the circuit tests normal, replace the PCM.

4. Ignition OFF, test for less than 5 ohm between the low reference circuit terminal B and ground.

⇒	If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the PCM.

5. 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, short to EGR Control circuits or an open/high resistance. If the circuit tests normal, replace the PCM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PCM.

6. Verify the EGR Position 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 PCM.

7. Install a 3A fused jumper wire between the signal circuit terminal C and the 5-volt reference circuit terminal D. The EGR Position Sensor parameter should display more than 90 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 PCM.

8. If all circuits test normal, replace the EGR valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.