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Home >> Toyota >> 1997 >> Camry LE, 2.2 G >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes - 2.2L >> Circuit Tests >> DTC P0401: Insufficient 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. Check all EGR system vacuum hoses. Replace as necessary. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM E9 connector. Turn ignition on. Connect a jumper wire between ground and terminal No. 23 (Pink/Black wire) at ECM E9 connector.
  2. Apply air pressure to VSV port "E". See Figure. With jumper wire connected, VSV should be on. Air should flow from small filter on end of VSV. See Figure. Disconnect jumper wire. Air should flow from port "G". If VSV operates as specified, go to step  6. If VSV does not operate as specified, go to next step.
  3. Turn ignition off. Remove EGR VSV. VSV is located under air intake chamber assembly. Using ohmmeter, measure resistance between valve terminals. Resistance should be 33-39 ohms at 68°F (20°C). Check for continuity between each terminal and body of VSV. If continuity exists, replace VSV. If continuity does not exist, go to next step.
  4. Check VSV operation. Apply battery voltage to VSV terminals. Air should flow from small filter on end of VSV. Remove battery voltage from valve terminals. Air should flow from port "G". Replace VSV as necessary.
  5. Check for open or short circuit in wiring harness between engine compartment fuse block and ECM. See appropriate wiring diagram in WIRING DIAGRAMS - 2.2L article. Repair wiring as necessary.
  6. Check EGR vacuum modulator. See SYSTEM/COMPONENT TESTS - 2.2L article. Replace EGR vacuum modulator as necessary. If EGR vacuum modulator is okay, check EGR valve. See SYSTEM/COMPONENT TESTS - 2.2L article. Replace EGR valve as necessary. If EGR valve is okay, go to next step.
  7. Check Manifold Absolute Pressure (MAP) sensor. See SYSTEM/COMPONENT TESTS - 2.2L article. Replace MAP sensor as necessary. If MAP sensor is okay, replace ECM and retest.
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