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Home >> Toyota >> 1996 >> Avalon XLS >> 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 Toyota Scan Tester)
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Diagnosis & Repair (Using Toyota Scan Tester)

  1. Connect scan tester. See Figure. Turn ignition on. Read EGR gas temperature. If temperature is 302°F (150°C), go to step 4). If temperature is not 302°F (150°C), go to next step. If temperature displayed is 318.7°F (159.3°C), there is a short in EGR temperature sensor circuit.
  2. Disconnect EGR temperature sensor connector. Sensor is mounted in manifold running from EGR valve to throttle body. Read EGR gas temperature. If EGR gas temperature is not 37.6°F (3.1°C), go to next step. If temperature is 37.6°F (3.1°C), replace sensor and retest.
  3. Turn ignition off. Access ECM behind glove box. Disconnect ECM E6 connector. See Figure. Turn ignition on. Using scan tester, read EGR gas temperature. If EGR gas temperature is 37.6°F (3.1°C), inspect and repair open in circuits between ECM and EGR temperature sensor. If temperature is not 37.6°F (3.1°C), replace ECM and retest.
  4. Inspect VSV. On scan tester, select ACTIVE TEST mode. Check operation of VSV when activated by scan tester. VSV is located under intake plenum cover. Start and run engine. With EGR system in OFF mode, air should exhaust from small filter on end of valve. See Figure. With EGR system in ON mode, air should pass through 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 valve terminals. Resistance should be 33-39 ohms at 68°F (20°C). Measure resistance between each terminal and body of valve. Resistance should be infinite. Replace VSV as necessary.
  6. Check VSV operation. Apply battery voltage to valve terminals. Air should exhaust from small filter on end of valve. See Figure. Remove battery voltage from valve terminals. Air should pass th rough valve. Replace VSV as necessary.
  7. If valve meets all specifications in steps 5) and 6), inspect circuits for short between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
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