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Home >> Lexus >> 1996 >> LX 450 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0402 - Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (Using OBD-II Scan Tester)

Diagnosis & Repair (Using OBD-II Scan Tester)

  1. Disconnect EGR temperature sensor. Using ohmmeter, measure resistance between sensor terminals. If resistance is 2500 ohms or more, go to next step. If resistance is less than 2500 ohms, replace sensor.
  2. Inspect circuits between EGR temperature sensor and ECM for short. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuits are okay, go to next step.
  3. Access ECM behind right instrument panel speaker. Ensure ignition is off. Disconnect ECM E4 connector. Turn ignition on. Connect a jumper wire between ground and terminal No. 22 (Blue/White wire) at ECM E4 connector.
  4. With jumper wire connected, Vacuum Switching Valve (VSV) is on. Air from port "G" should not exhaust from port "E". See Figure. Disconnect jumper wire. Air from port "G" should exhaust from port "E". If valve operates correctly, check EGR valve. See SYSTEM/COMPONENT TESTS article. If VSV does not operate correctly, go to next step.
  5. Remove EGR VSV. Air intake chamber may have to be removed to access VSV. Using ohmmeter, measure resistance between VSV terminals. Resistance should be 30-34 ohms at 68°F (20°C). Check for continuity between each VSV terminal and body of valve. If continuity exists, replace VSV. If continuity does not exist, go to next step.
  6. Check for an open circuit in wiring harness between VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.
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