Test W: Exhaust Gas RECIRCULATION: Testing

WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: The Powertrain Control Module (PCM) harness connectors must be properly seated and the connector latch properly attached to eliminate possible driveability concerns or a no-start condition. Installing PCM connectors on an angle may cause a bad connection, misdiagnosis and damaged components. Install the connector on where the lever pivots and seats itself. Apply light pressure to get the connector into position on the PCM lever to fully seat the connector.

NOTE: When the PCM engine harness connector is disconnected additional DTCs will be set. All DTCs must be cleared before returning the vehicle to service.

1) Preliminary Diagnosis For DTCS P0401, P0402, P0403, P0404, P0405 & P0406

Perform visual inspection. Connect the scan tool. Retrieve and record any continuous and on-demand DTCs. Record freeze frame data. Clear all DTCs. Perform the KOEO ON-DEMAND SELF-TEST under QUICK TEST. Are any DTCs retrieved? If yes, proceed as follows:
- For P0401 and P0402, go to next step.
- For P0403, go to step 4).
- For P0404, go to step 9).
- For P0405, go to step 10).
- For P0406, go to step 14).
If no, unable to duplicate condition. Check for loose connections, damaged or corroded terminals or pins. Wiggle harness attempting to recreate fault. Repair as necessary. See TROUBLE SHOOTING - NO CODES - 6.0L DIESEL article if a driveability concern exists.

2) DTC P0401 & P0402

Possible causes are:
- EGR valve stuck or sticking.
- EGR valve position sensor bias.
Perform the KOEO ON-DEMAND SELF-TEST under QUICK TEST. Are other DTCs present? If yes, repair all other DTCs before diagnosing DTC P0401 or P0402. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.

3) Check EGR Valve Operation

EGR valve override control with the engine running is 45% maximum duty cycle. With the KOEO, duty cycle can be controlled to 85%. Access EBP, EGRVPDES, EGRDC, EGRVP PIDS. Record readings. Start engine. Using scan tool, activate Output State Control for EGR valve. Monitor EBP while increasing and decreasing EGRDC. Does EBP reading indicate EGR valve movement? If yes, Clear DTCs and retest the system. If other DTCs are present, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If a driveability concern is present or DTC P0401 or P0402 is present, see TEST 8: EGR POSITION in SYSTEM & COMPONENT TESTING - 6.0L DIESEL article. If no, install a new EGR valve. Restore the vehicle. Clear DTCs and retest the system.

4) DTC P0403

Possible causes are:
- Open in control circuit.
- Control circuit shorted to voltage.
- Control circuit shorted to ground.
- Faulty EGR actuator.
- Faulty PCM.
Disconnect the EGR actuator electrical harness connector. Key on. Measure the voltage between EGR actuator valve harness connector terminal "E" and ground. See Figure. Is the voltage above 11.0 volts? If yes, go to next step. If no, repair open in VPWR circuit. Restore the vehicle. Clear DTCs and retest the system.

5) Check EGR Actuator Control Valve Circuit For A Short To Voltage

Key off. Disconnect the PCM engine harness connector C1381C. Key on. Measure the voltage between EGR actuator valve harness connector terminal "A" and ground. Is the voltage less than 0.2 volt? If yes, go to next step. If no, repair short to voltage. Restore the vehicle. Clear DTCs and retest the system.

6) Check EGR Actuator Control Valve Circuit For A Short To Voltage

Key off. Measure the resistance between EGR actuator valve harness connector terminal "A" and ground. Is the resistance greater than 10,000 ohms? If yes, go to next step. If no, repair short to ground. Restore the vehicle. Clear DTCs and retest the system.

7) Check EGR Control Circuit For An Open

Measure the resistance between EGR actuator harness connector terminal "A" and PCM engine harness connector C1381C terminal No. 23. See CONTROL MODULE CONNECTOR IDENTIFICATION . Is the resistance less than 0.5 ohm? If yes, go to next step. If no, repair open in control circuit. Restore the vehicle. Clear DTCs and retest the system.

8) Check EGR Actuator

Measure the resistance between EGR actuator (component side) terminals "A" and "E". Is the resistance 4.0-10.0 ohms? If yes, install a new PCM. Restore the vehicle. Clear DTCs and retest the system. If no, install a new EGR actuator. Restore the vehicle. Clear DTCs and retest the system.

9) DTC P0404

Possible causes are:
- Faulty EGR valve.
- Restricted EGR flow.
- Faulty PCM.
Are other DTCs present? If yes, repair other DTCS before diagnosing DTC P0404. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, install a new EGR valve. Restore the vehicle. Clear DTCs and retest the system.

10) DTC P0405

Possible causes are:
- Position signal circuit shorted to ground.
- Position signal circuit open.
- Faulty actuator.
- Faulty PCM.
Disconnect the EGR actuator valve electrical connector. Key on. Measure the voltage between EGR harness connector terminals "B" and "D". See Figure. Is the voltage 4.5-5.5 volts? If yes, go to next step. If no, repair open in VREF or signal return circuit. Restore the vehicle. Clear DTCs and retest the system.

11) Check EGR Position Signal Circuit For A Short To Ground

Key off. Disconnect the PCM engine harness connector C1381C. Measure the resistance between EGR harness connector terminal "C" and ground. Is the resistance greater than 10,000 ohms? If yes, go to next step. If no, repair short to ground in position signal circuit. Restore the vehicle. Clear DTCs and retest the system.

12) Check EGR Position Signal Circuit For An Open

Measure the resistance between PCM engine harness connector C1381C terminal No. 33, and EGR actuator connector terminal "C". See CONTROL MODULE CONNECTOR IDENTIFICATION . Is the resistance less than 0.5 ohm? If yes, go to next step. If no, repair open in EGR position signal circuit. Restore the vehicle. Clear DTCs and retest the system.

13) Check EGR Internal Circuits For An Open Or Short

Measure the resistance of EGR (component) internal circuits.
- Terminals "D" and "C": 1300-1330 ohms.
- Terminals "C" and "B": 4275-4285 ohms.
- Terminals "B" and "D": 4515-4525 ohms.
Are all measurements within range? If yes, install a new PCM. Restore the vehicle. Clear DTCs and retest the system. If no, install a new EGR actuator. Restore the vehicle. Clear DTCs and retest the system.

14) DTC P0406

Possible causes are:
- Position signal shorted to voltage.
- Open in signal return circuit.
- Faulty sensor.
- Faulty PCM.
Induce opposite failure. Disconnect EGR actuator harness connector. Perform the KOEO ON-DEMAND SELF-TEST under QUICK TEST. Is DTC P0405 present? If yes, install a new EGR actuator. Restore the vehicle. Clear DTCs and retest the system. If no, go to next step.

15) Check EGR Position Signal Circuit For A Short To Voltage

Key off. Disconnect the PCM engine harness connector. Key on. Measure the voltage between EGR actuator connector terminal "C" and ground. See Figure. Is the voltage less than 0.2 volt? If yes, go to next step. If no, repair short to voltage in EGR position signal circuit. Restore the vehicle. Clear DTCs and retest the system.

16) Check EGR Position Signal Circuit Signal Return For An Open

Key off. Reconnect PCM. Measure the resistance between EGR harness connector terminal "B" and ground. Is the resistance less than 0.5 ohm? If yes, install a new PCM. Restore the vehicle. Clear DTCs and retest the system. If no, repair open in signal return circuit. Restore the vehicle. Clear DTCs and retest the system.