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Home >> Lexus >> 1996 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0402 - Excessive EGR Flow Detected >> Diagnosis & Repair (Using OBD-II Scan Tester)
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Diagnosis & Repair (Using OBD-II Scan Tester)

  1. Disconnect EGR temperature sensor. Connector is located underneath throttle body. Using ohmmeter, measure resistance between sensor terminals. If resistance is 2500 ohms or more (not immediately after driving), go to next step. If resistance is less than 2500 ohms, replace sensor and retest.
  2. Inspect circuits between EGR temperature sensor and ECM for short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
  3. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM E9 harness connector. See Figure. Turn ignition on. Connect a jumper wire between ground and terminal No. 12 (Black/Blue wire) at ECM E9 connector. VSV is located under intake plenum cover.
  4. With jumper wire connected, VSV is on. Air should exhaust through filter on end of valve. Disconnect jumper wire. Air should pass through valve and exit vacuum fitting at bottom of valve. If valve does not operate correctly, go to next step. If valve operates correctly, inspect EGR valve. See SYSTEM/COMPONENT TESTS article. Replace EGR valve as necessary.
  5. Turn ignition off. Remove EGR VSV. Using ohmmeter, measure resistance between VSV terminals. Resistance should be 26-46 ohms. Measure resistance between each terminal and body of VSV. Resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, replace VSV.
  6. Using jumper wires, apply battery voltage to VSV terminals. Air should exhaust from small filter on end of valve. Remove jumper wires from VSV terminals. Air should pass through valve. Replace VSV as necessary.
  7. If valve meets all specifications in steps 5) and 6), inspect circuits between EGR 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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