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Home >> Toyota >> 1997 >> Previa DX, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Circuit Tests >> DTC P0402: Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (Using OBD-II Scan Tool)
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Diagnosis & Repair (Using OBD-II Scan Tool)

  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. Check for short circuit in wiring harness between EGR temperature sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Access ECM under driver's seat. Ensure ignition is off. Disconnect ECM E9 connector. Turn ignition on. Connect a jumper wire between ground and terminal No. 16 (Red/Black wire) at ECM E9 connector.
  4. With jumper wire connected, Vacuum Switching Valve (VSV) is on. Apply air pressure to VSV port "E". Air from port "E" should flow from port "F". See Figure. Disconnect jumper wire. Air from port "E" should flow from filter on end of valve. 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. Using ohmmeter, measure resistance between VSV terminals. Resistance should be 37-44 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 short circuit in wiring harness between VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace ECM and retest.
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