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P0405






P0405-EGR POSITION SENSOR CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The EGR Valve is opened by a motor located on top of the EGR valve. The EGR Valve is spring loaded closed. The motor electronically opens the valve and is controlled by the ECM. The EGR Valve motor contains three position sensors that detect to location of the EGR Valve. These sensors report the position of the valve back to the ECM over the EGR position signal wires. This diagnostic monitors the EGR solenoid driver circuits. If there is a short of open circuit detected for more than a calibrated period of time then the diagnostic will fail. The ECM lights the MIL lamp immediately after this diagnostic runs and fails. During this time the ECM will stop controlling the EGR valve. The default position for the valve is closed. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
Ignition on and battery voltage greater than 9 volts.

- Set Condition:
All three EGR Valve position sensors are reading either High or Low for five seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: The EGR Valve harness connector is difficult to lock on to the valve. A connector not locked on completely will cause this DTC to set.

NOTE: If there are any 5-volt supply DTCs present, repair those DTCs before proceeding.

1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Start the vehicle. It may be necessary to drive vehicle to reset DTC.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION - DIESEL (Diagnostic Procedure). Intermittent Condition Test.

2. (F855) 5-VOLT SUPPLY OPEN




1. Turn the ignition off.
2. Disconnect the EGR Valve harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Turn the ignition on, engine not running.
4. Measure the voltage of the (F855) 5-volt Supply circuit at the EGR Valve harness connector.

Is the voltage reading 5.0 volts?

Yes

- Go To 3

No

- Repair the (F855) 5-volt Supply circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. EGR POSITION SIGNAL CIRCUITS SHORTED TO VOLTAGE




1. Measure the voltage of the (K683) EGR Position Sensor Signal 1 circuit at the EGR Valve harness connector.
2. Measure the voltage of the (K685) EGR Position Sensor Signal 2 circuit at the EGR Valve harness connector.
3. Measure the voltage of the (K687) EGR Position Sensor Signal 3 circuit at the EGR Valve harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the appropriate circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. (K916) SENSOR GROUND OPEN




1. Turn the ignition off.
2. Disconnect the ECM C1 harness connector.
3. Measure the resistance of the (K916) Sensor Ground circuit between the EGR Valve harness connector and the ECM C1 harness connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 5

No

- Repair the open or high resistance in the (K916) Sensor Ground circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. EGR POSITION SIGNAL CIRCUITS OPEN




1. Measure the resistance of the (K683) EGR Position Sensor Signal 1 circuit between the EGR Valve harness connector and the (K916) Sensor Ground circuit.
2. Measure the resistance of the (K685) EGR Position Sensor Signal 2 circuit between the EGR Valve harness connector and the (K916) Sensor Ground circuit.
3. Measure the resistance of the (K687) EGR Position Sensor Signal 3 circuit between the EGR Valve harness connector and the (K916) Sensor Ground circuit.

Is the resistance less than 10 ohms?

Yes

- Go To 6

No

- Repair the open or high resistance in the appropriate circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. EGR POSITION SIGNAL CIRCUITS SHORTED TO GROUND




1. Measure the resistance between ground and the (K683) EGR Position Sensor Signal 1 circuit at the ECM harness connector.
2. Measure the resistance between ground and the (K685) EGR Position Sensor Signal 2 circuit at the ECM harness connector.
3. Measure the resistance between ground and the (K687) EGR Position Sensor Signal 3 circuit at the ECM harness connector.

Is the resistance less than 10k ohms?

Yes

- Repair the short to ground in the appropriate circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 7

7. EGR VALVE
1. Reconnect the ECM C1 harness connector.
2. Replace the EGR Valve.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Start the vehicle. It may be necessary to drive vehicle to reset DTC.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Replace ECM.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair complete.

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