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Home >> Toyota >> 1998 >> Avalon XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Self-Diagnostic Tests >> DTC P0441: Incorrect EVAP Purge Flow Or DTC P0446: EVAP Vent Control Fault >> Diagnosis & Repair (Using OBD-II Scan Tool Except Calif. Emission Models Without Engine Immobilizer System &/Or Traction Control)
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Diagnosis & Repair (Using OBD-II Scan Tool Except Calif. Emission Models Without Engine Immobilizer System &/Or Traction Control)

  1. Check EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor wiring harness connectors for damaged pins, corrosion and loose wires. For component locations, see appropriate illustration in THEORY/OPERATION article. Repair connectors as necessary. If connectors are okay, go to next step.
  2. Check all EVAP related vacuum hoses for cracks, looseness and correct routing. For proper vacuum hose routing, see appropriate illustration in VACUUM DIAGRAMS article. Repair vacuum hoses as necessary. If vacuum hoses are okay, go to next step.
  3. Access ECM behind glove box. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 1 (Blue/Red wire) and No. 22 (Brown wire) at ECM E7 connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
  4. Backprobing ECM connector, measure voltage between terminal No. 13 (Pink wire) at ECM E6 connector and terminal No. 22 (Brown wire) at ECM E7 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is mounted on firewall, near brake booster. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied and 1.3-2.1 volts with .59 in. Hg (2 kPa) applied, go to step 6). If voltage is not as specified, go to next step.
  5. Check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace vapor pressure sensor.
  6. Disconnect EVAP VSV vacuum hoses. EVAP VSV is located on front top of engine. Apply air pressure to VSV port "E". See Figure. Air should not flow from port "F". Access ECM behind glove box. Turn ignition on. Connect a jumper wire between ground and terminal No. 2 (Black/Red wire) at ECM E6 connector. See Figure. Air should flow from port "F". If VSV functions as specified, go to step 9). If VSV does not function as specified, go to next step.
  7. Check vacuum hose between intake manifold and EVAP VSV, and hose between EVAP VSV and charcoal canister. Replace vacuum hoses as necessary. If vacuum hoses are okay, check EVAP VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM/COMPONENT TESTS article. Replace VSV as necessary. If VSV is okay, go to next step.
  8. Check for an open or short in wiring harness between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace ECM.
  9. Disconnect vapor pressure sensor VSV vacuum hoses. VSV is mounted on top of EVAP charcoal canister on left side of engine compartment. Apply air pressure to VSV port "E". See Figure. Air should flow from port "G". Access ECM behind glove box. Turn ignition on. Connect a jumper wire between ground and terminal No. 8 (White/Blue wire) at ECM E6 connector. See Figure. Air should flow from port "F". If VSV does not function as specified, go to next step. If VSV functions as specified, check charcoal canister. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM/COMPONENT TESTS article. Replace charcoal canister as necessary.
  10. Check vapor pressure sensor VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM/COMPONENT TESTS article. Replace VSV as necessary. If VSV is okay, go to next step.
  11. Check for open or short circuit in wiring harness between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring harness as necessary. If wiring harness is okay, replace ECM.
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