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1-5-4 (EGR System Leakage)

  1. Symptom of EGR system leakage is rough idle. Code will set when engine temperature is 150°F (65°C) or less, and temperature sensor detects an increasing temperature. If ECU detects that temperature of EGR temperature sensor varies by more than a preset limit before temperature has reached 150°F (65°C), ECU will interpret condition as an EGR flow and will initiate a code. Some faults that can produce this code include:
    • Leaking EGR valve.
    • Signal to EGR controller faulty.
    • EGR controller defective.
    • Poor ground.
    • Engine thermostat defective.
  2. Start engine and listen to idle. If idle is okay, go to step 4) and check engine temperature. If idle is not okay, disconnect EGR controller connector. If idle is still rough, go to next step and check EGR controller. If idle is now okay, check Green/Brown wire between ignition ECU terminal for a short to ground.
  3. To check EGR controller, run engine at idle. Carefully disconnect Yellow hose from EGR controller. If idle is now okay, repeat test using new EGR controller. If idle is still rough, turn ignition off. Carefully disconnect Yellow hose from EGR valve. Check hose for blockage or leaks. If Yellow hose is okay, repeat test using new EGR valve. If hose is blocked or leaking, replace hose. In both cases, clear codes.
  4. Check engine temperature gauge with engine running. If gauge pointer does not rise to normal and top radiator hose is hot, go to next step. If gauge shows normal operating temperature and top radiator hose is hot, go to step 6). If gauge pointer rises slowly and top radiator hose is not at normal operating temperature, retest system using new thermostat. Clear codes.
  5. Turn ignition off. Disconnect Mass Airflow (MAF) sensor connector. Connect an ohmmeter between MAF sensor connector terminal No. 2 and ground. See Figure . If ohmmeter indicates about zero ohms, go to next step. If ohmmeter does not indicate about zero ohms, disconnect electrical connector located under intake manifold, on engine block. Clean and reconnect connector. Clear codes.
  6. Code may be set by contact resistance at EGR and engine temperature sensor connector. Clean and protect EGR and engine temperature sensor connectors from oxidation, dirt, etc. Clear codes.
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