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Engine Management

EGR Valve

 
  • Efficient way of reducing vehicle emissions

Troubleshooting

  • Symptoms:
    • Loss of engine power
    • Engine stuttering or jumping
    • Car falling into ‘limp mode’
    • Black smoke appearing from exhaust
  • Possible causes for failure:
    • Carbon deposits left by re-circulated exhaust gases causing the valve to stick
    • Damaged solenoid valve preventing mechanical EGR valve from actuating

Testing:

When inspecting an EGR valve it is important that protective gloves are worn as it can become extremely hot when the engine is running. Note: on OBD monitored EGR valves the vehicle must be in gear for operating instructions to be received. If the vehicle is not in gear, the engine will give the impression of restricted exhaust gas flow when this is not the case.

  1. The first check is to find out whether the valve can move and operate freely as it may be stuck or carbonised.

Inspect the valve movement when the accelerator is depressed.

Note: at full throttle there is no EGR flow so it is important that this is checked at a lower depression. If the valve moves in sequence with the accelerator then the valve is neither stuck nor carbonised.

You can also use a pressure hand pump on pneumatic valves by connecting the tool to the inlet valve to see whether the valve operates under normal conditions

  1. Next, inspect the hose connections to the EGR valve. These may become clogged or damaged over time, resulting in no exhaust gas flow. If they are clogged they will need replacing to ensure airflow is at the required rate.

Other components to check:

  • Air mass sensor – a faulty air mass sensor may not be measuring the airflow rate correctly
  • Throttle body – if the throttle body is malfunctioning this may result in an insufficient amount of air entering the engine
  • Vacuum pump – pneumatically controlled EGR valves may fail to actuate if the vacuum pump is not operating correctly

Common Fault Codes

  • P0382 Exhaust Gas Recirculation Flow Malfunction
  • P0400 Exhaust Gas Recirculation Flow Malfunction
  • P0401 Exhaust Gas Recirculation Flow Insufficient Detected
  • P0402 Exhaust Gas Recirculation Flow Excessive Detected
  • P0403 Exhaust Gas Recirculation Circuit Malfunction
  • P0404 Exhaust Gas Recirculation Circuit Range/Performance
  • P0405 Exhaust Gas Recirculation Sensor A Circuit Low
  • P0406 Exhaust Gas Recirculation Sensor A Circuit High
  • P0407 Exhaust Gas Recirculation Sensor B Circuit Low
  • P0408 Exhaust Gas Recirculation Sensor B Circuit High

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