Staff Answer
Jun 24, 2026 - 08:59 PM
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The P0402 code refers to Exhaust Gas Recirculation (EGR) Flow Excessive Detected. It means the engine computer has detected that too much exhaust gas is recirculating into the intake manifold, often causing rough idling or engine stalling.
Common Troubleshooting Steps:
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Check the EGR Valve: The valve may be stuck in the "open" position due to carbon buildup. Removing and cleaning the valve can often restore proper function.
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Inspect the Vacuum System: If your vehicle uses a vacuum-operated EGR system, check all vacuum lines for cracks, leaks, or incorrect routing.
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Test the EGR Solenoid: A faulty vacuum control solenoid may keep the EGR valve open when it should be closed. Test the solenoid for proper electrical operation.
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Verify Sensor Accuracy: Use an OBD-II scanner to monitor the EGR position sensor data; a faulty sensor may send incorrect feedback to the ECM, causing it to trigger the code falsely.
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