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Home >> Lexus >> 1997 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0402 - Excessive EGR Flow Detected >> Diagnosis & Repair
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Diagnosis & Repair

  1. Check all EGR system vacuum hoses. Replace hoses as necessary and retest system. If vacuum hoses are okay, check EGR VSV. Using scan tool, select ACTIVE TEST mode. Check operation of VSV when activated by scan tool. VSV is located near air intake chamber assembly.
  2. Start and run engine. With EGR system off, air should flow from port "G". See Figure. With EGR system on, air should flow from port "F". If valve operates correctly, go to step 6). If valve does not operate correctly, go to next step.
  3. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 27-33 ohms. Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, replace VSV.
  4. Apply air pressure to port "E". Air should flow from port "G". Using jumper wires, apply battery voltage to VSV terminals. Again, apply air pressure to port "E". Air should flow from port "F". Replace VSV as necessary and retest system.
  5. If valve meets all specifications in steps 3) and 4), check wiring harness between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary and retest system.
  6. Check EGR valve. See SYSTEM/COMPONENT TESTS article. Replace EGR valve as necessary and recheck system. If EGR valve is okay, check EGR valve position sensor. See SYSTEM/COMPONENT TESTS article. Replace sensor as necessary and retest system. If sensor is okay, replace ECM and retest system.
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