P0402

P0402-EGR FLOW EXCESSIVE DETECTED





For a complete wiring diagram, consult the Wiring Information.

Theory of Operation

The purpose of this monitor is to check if the Exhaust Gas Recirculation (EGR) flow is higher than commanded. The diagnostic closes the EGR valve, and limits the EGR Throttle Control Valve. It then looks at fresh air flow fraction and the difference in pressure between the Exhaust Gas Pressure sensor and Boost Pressure sensor to determine if the EGR valve is leaking. The Powertrain Control Module (PCM) will illuminate the MIL lamp after the diagnostic runs and fails in two consecutive drive cycles. The PCM will also illuminate the ETC lamp. The MIL lamp will turn off once the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
Engine running, at idle, coolant temperature above a calibrated threshold, intake manifold temperature above a calibrated threshold, EGR valve is closed.

- Set Condition:
EGR Throttle Control Valve closed, EGR fraction increases more than a calibrated threshold.





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

1.

NOTE: If other EGR related DTCs are present and active, repair those DTCs before proceeding.
ACTIVE DTCs
1. Ignition on, engine not running.
2. With the scan tool, check for active DTCs.

Is the DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. CHECK THE THERMOSTAT OUTLET FOR A RESTRICTION
1. Turn the ignition off.
2. Remove the Exhaust Gas Pressure sensor from the thermostat outlet.
3. Inspect the Exhaust Gas Pressure sensor and the thermostat outlet for build up or debris.

Are the Exhaust Gas Pressure Sensor and the thermostat outlet free of debris?

Yes

- Go To 3

No

- Remove debris from Exhaust Gas Pressure Sensor and the thermostat outlet.
- Go To 3

3. CHECK THE EXHAUST GAS PRESSURE SENSOR TUBE
1. Remove the steel tube from the exhaust manifold to the Exhaust Gas Pressure Sensor port.

Is the tube free from debris?

Yes

- Go To 4

No

- Clean the tube and reinstall.
- Go To 4

4. CHECK THE EXHAUST SYSTEM
1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS diagnostic procedure. Checking The Exhaust System For Leaks

Was an Exhaust System leak found?

Yes

- Repair the Exhaust System leak.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L Procedure. Component Tests and General Diagnostics

No

- Go To 5

5. CHECK THE INTAKE SYSTEM
1. Perform INTAKE AIR SYSTEM PRESSURE TEST diagnostic procedure. Intake Air System Pressure Test

Was an Intake System leak found?

Yes

- Repair the Intake Air System leak.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L Procedure. Component Tests and General Diagnostics

No

- Go To 6

6. CHECK THE EGR AIRFLOW THROTTLE CONTROL VALVE
1. Remove the boot from the EGR Throttle Control Valve. Using a mirror, look at the butterfly valve on the inside of the EGR Throttle Control Valve.
2. Start the vehicle, let idle for 10 seconds.
3. Turn ignition off.

NOTE: If functioning properly the EGR Throttle Control Valve will close immediately after the engine is shut down.

Did the EGR Throttle Control Valve close immediately after the engine was shut down?

Yes

- Go To 7

No

- Replace the EGR Airflow Control Valve.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L Procedure. Component Tests and General Diagnostics

7. CHECK THE EGR VALVE
1. Ignition on, engine not running.
2. With the scan tool, erase DTC.
3. Turn the ignition off for 75 seconds.
4. Start engine and let idle to operating temperature.

Is DTC still active?

Yes

- Remove and clean the EGR valve with Mopar EGR Valve cleaner. Procedures.
- Go To 8

No

- Repair complete.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L Procedure. Component Tests and General Diagnostics

8. ACTIVE DTC
1. Ignition on, engine not running.
2. With the scan tool, erase DTC.
3. Turn the ignition off for 75 seconds.
4. Start engine and let idle to operating temperature.

Is DTC still active?

Yes

- Replace EGR Valve.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L Procedure. Component Tests and General Diagnostics

No

- Repair complete.
- Perform the DIESEL AFTERTREATMENT VALIDATION - 6.7L Procedure. Component Tests and General Diagnostics