LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2001 >> ES 300 >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0441: Incorrect EVAP Purge Flow Or DTC P0446: EVAP Vent Control Circuit Fault >> Diagnosis & Repair (Using Lexus Scan Tool)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair (Using Lexus Scan Tool)

WARNING: This page is about a different car, the 2003 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect the hand-held tester to the DLC3. Select the ENHANCED OBD2/SYSTEM CHECK/EVAP SYS CHECK (or EVAP LEAK TEST) mode on the hand-held tester. Perform EVAP SYS CHECK (or EVAP LEAK TEST). If scan tool detects a leak on fuel tank side, go to next step. If scan tool detects a leak on canister side, go to step  23. If scan tool detects a leak on EVAP system, go to step  41.
  2. Check that fuel tank cap is LEXUS genuine parts. Replace as necessary. If okay, go to next step.
  3. Check that fuel tank cap is correctly installed. Correctly install as necessary. If okay, go to next step.
  4. Check fuel tank cap. Replace as necessary. If okay, go to next step.
  5. Check filler neck for damage. Repair as necessary. If okay, go to next step.
  6. Connect the hand-held tester to the DLC3. Select the ENHANCED OBD2/ACTIVE TEST mode on the hand-held tester. Disconnect the vacuum hose for the VSV for the EVAP from the charcoal canister. Start the engine. Select the item EVAP (ALON)/ALL in the ACTIVE TEST and operate VSV for EVAP. When the VSV for the EVAP is operated by the hand-held tester, check whether the disconnected hose applies suction to your finger. If VSV is on, disconnected hose applies suction to your finger. If VSV is OFF, disconnected hose applies no suction to your finger. See Fig 1. If vacuum is not as specified, go to next step. If vacuum is as specified, go to step  10.
    Fig 1: Checking VSV Operation
    G00239876Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  7. Check vacuum hose between intake manifold and VSV for EVAP, and vacuum hose between VSV for EVAP and charcoal canister. If problem exists, replace vacuum hoses as necessary. If problem does not exist, go to next step.
  8. Check EVAP VSV operation. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If problem exists, replace EVAP VSV. If problem does not exist, go to next step.
  9. Check for an open or short in wiring between EFI or ECD main relay, EVAP VSV and ECM. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  10. Disconnect the vacuum hose for the VSV for the CCV from the charcoal canister. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ENHANCED OBD2/ACTIVE TEST mode on hand-held tester. Select INTAKE CTL VSV/ALL in the ACTIVE TEST and operate VSV for EVAP. Check VSV operation when it is operated by the hand-held tester. When VSV is ON, air does not flow from port "E" to port "F". When VSV is OFF, air from port "E" flows out through port "F". See Fig 2. If VSV operates as specified, go to step  14. If VSV does not operate as specified, go to next step.
    Fig 2: Checking VSV For CCV
    G00239877Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  11. Check vacuum hose between VSV for CCV and charcoal canister. Repair as necessary. If okay, go to next step.
  12. Check operation of VSV for CCV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If okay, go to next step. If not okay, replace VSV for CCV.
  13. Check for open and short in harness and connector between EFI or ECD relay and VSV for CCV, and VSV for CCV and ECM. Repair as necessary. If okay, replace ECM.
  14. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ENHANCED OBD2/ACTIVE TEST mode on the hand-held tester. Select the item TANK BYPASS VSV/ALL in the ACTIVE TEST and operate VSV for EVAP. Check the VSV operation when it is operated by the hand-held tester. When VSV is ON, air from port "E" flows through port "F". When VSV is OFF, air does not flow from port "E" to port "F". See Fig 3. If okay, go to step  17. If not okay, go to next step.
    Fig 3: Checking VSV For Pressure Switching Valve
    G00239878Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  15. Check operation of VSV for pressure switching valve. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If okay, go to next step. If not okay, replace VSV for pressure switching valve.
  16. Check for open and short in harness and connector between EFI or ECD relay and VSV for pressure switching valve, and VSV for pressure switching valve and ECM. Repair as necessary. If okay, check and replace ECM.
  17. Check whether hose close to fuel tank has been modified, and check whether there are signs of any accident near fuel tank. See Fig 4. Repair as necessary. If okay, go to next step.
    Fig 4: Checking Fuel Tank & Fuel Tank Hoses
    G00239879Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  18. Check vacuum hoses between vapor pressure sensor and fuel tank, and charcoal canister and VSV for pressure switching valve. Repair as necessary. If okay, go to next step.
  19. Check hose and tube between fuel tank and charcoal canister. Repair as necessary. If okay, go to next step.
  20. Remove the glove compartment door. Turn the ignition switch ON. Measure the voltage between terminals VC and E2 of the ECM connector. See Fig 5. If voltage is 4.5-5.5 volts, go to next step. If not, replace ECM.
    Fig 5: Checking Voltage Between ECM Connector Terminals VC & E2
    G00239880Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  21. Measure the voltage between terminals PTNK and E2 of the ECM connectors. Disconnect the vacuum hose from the vapor pressure sensor. See Fig 6. Using the MITYVAC (hand-held vacuum pump) apply a vacuum of 1.18 in. Hg (30 mm Hg) to the vapor pressure sensor. The vacuum applied to the vapor pressure sensor must be less than 19.7 in. Hg (500 mm Hg). If voltage is 2.9-3.7 volts with vacuum hose disconnected, then drops to .5 volts or less, it is likely that vehicle user did not properly close fuel tank cap. If voltage is not to specification, go to next step.
    Fig 6: Checking Voltage At ECM Connector Terminals E2 & PTNK
    G00239881Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  22. Check for open and short in harness and connector between vapor pressure sensor and ECM. Repair as necessary. If okay, replace vapor pressure sensor.
  23. Connect the hand-held tester to the DLC3. Select the ENHANCED OBD2/ACTIVE TEST mode on the hand-held tester. Disconnect the vacuum hose for the VSV for the EVAP from the charcoal canister. Start the engine. Select the item EVAP (ALON)/ALL in the ACTIVE TEST and operate VSV for EVAP. When VSV for the EVAP is operated by the hand-held tester, check whether the disconnected hose applies suction to your finger. If VSV is ON, disconnected hose applies suction to your finger. If VSV is OFF. disconnected hose applies no suction to your finger. See Fig 1. If okay, go to step  27. If not okay, go to next step.
  24. Check vacuum hose between intake manifold and VSV for EVAP, and VSV for EVAP and charcoal canister. Repair as necessary. If okay, go to next step.
  25. Check operation of VSV for EVAP. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. Repair as necessary. If okay, go to next step.
  26. Check for open and short in harness and connector between EFI or ECD relay and VSV for EVAP, and VSV for EVAP, and VSV for EVAP and ECM. Repair as necessary. If okay, check and replace ECM.
  27. Disconnect the vacuum hose for the VSV for the CCV from the charcoal canister. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ENHANCED OBD2/ACTIVE TEST mode on the hand-held tester. Select the item INTAKE CTL VSV/ALL in the ACTIVE TEST and operate VSV for EVAP. Check the VSV operation when it is operated by the hand-held tester. If VSV is ON, air does not flow from port "E" to port "F". If VSV is OFF, air from port "E" flows out through port "F". See Fig 2. If okay, go to step  31. If not okay, go to next step.
  28. Check vacuum hose between VSV for CCV and charcoal canister. Repair as necessary. If okay, go to next step.
  29. Check operation of VSV for CCV. Replace VSV for CCV as necessary. If okay, go to next step.
  30. Check for open and short in harness and connector between EFI or ECD relay and VSV for CCV, and VSV for CCV and ECM. Repair as necessary. If okay, check and replace ECM.
  31. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ENHANCED OBD2/ ACTIVE TEST mode on hand-held tester. Select the item TANK BYPASS VSV/ALL in the ACTIVE TEST and operate VSV for EVAP. Check VSV operation when it is operated by hand-held tester. If VSV is ON, air from port "E" flows out through port "F". If VSV is OFF, air does not flow from port "E" to port "F". See Fig 3. If okay, go to step  34. If not okay, go to next step.
  32. Check operation of VSV for pressure switching valve. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If okay, go to next step. If not okay, replace VSV for pressure switching valve.
  33. Check for open and short in harness and connector between EFI or ECD relay and VSV for pressure switching valve, and VSV for pressure switching valve and ECM. Repair or replace harness or connector. If okay, check and replace ECM.
  34. Check whether there are signs of any accident near charcoal canister. Repair as necessary. See Fig 4. If okay, go to next step.
  35. Check vacuum hoses No. 4, 5, 7 and 8. See Figure. Repair or replace as necessary.
  36. Check hose and tube between fuel tank and charcoal canister. Check for proper connection of the fuel tank and fuel evaporation pipe, fuel evaporation pipe, and fuel tube under the floor, fuel tube under the floor and charcoal canister. Repair or replace as necessary. If okay, go to next step.
  37. Check charcoal canister for cracks, hole and damage. Repair as necessary. If okay, go to next step.
  38. Remove the glove compartment door. Turn the ignition switch ON. Measure the voltage between terminals VC and E2 of the ECM connector. See Fig 5. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, check and replace ECM.
  39. Measure the voltage between terminals PTNK and E2 of the ECM connectors. Disconnect the vacuum hose from the vapor pressure sensor. Using the MITYVAC (hand-held vacuum pump), apply a vacuum of 1.18 in. Hg (30 mm Hg) to the vapor pressure sensor. The vacuum applied to the vapor pressure sensor must be less than 19.7 in. Hg (500 mm Hg). See Fig 6. If voltage is 2.9-3.7 volts when vacuum hose is disconnected, then drops to 0.5 volts when vacuum is applied, check and replace ECM. If not, go to next step.
  40. Check for open and short in harness and connector between vapor pressure sensor and ECM. Repair wiring as necessary. If okay, replace vapor pressure sensor.
  41. Connect the hand-held tester to the DLC3. Select the ENHANCED OBD2/ACTIVE TEST mode on hand-held tester. Disconnect the vacuum hose for the VSV for the EVAP from the charcoal canister. Start the engine. Select the item EVAP (ALON) ALL in the ACTIVE TEST and operate VSV for EVAP. When the VSV for the EVAP is operated by the hand-held tester, check whether the disconnected hose applies suction your finger. When VSV is ON, disconnected hose applies suction to your finger. When VSV is OFF, disconnected hose applies no suction to your finger. See Fig 1. If okay, go to step  45. If not okay, go to next step.
  42. Check vacuum hose between intake manifold and VSV for EVAP, and VSV for EVAP and charcoal canister. Repair as necessary. If okay, go to next step.
  43. Check operation of VSV for EVAP. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If okay, go to next step. If not okay, replace VSV for EVAP.
  44. Check for open and short in harness and connector between EFI or ECD relay and VSV for EVAP, and VSV for EVAP and ECM. If okay, check and replace ECM. If not okay, repair or replace harness or connector.
  45. Disconnect the vacuum hose for the VSV for the CCV from the charcoal canister. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ENHANCED OBD2/ACTIVE TEST mode on the hand-held tester. Select the item INTAKE CTL VSV/ALL in the ACTIVE TEST and operate VSV for EVAP. Check the VSV operation when it is operated by the hand-held tester. When VSV is ON, air does not flow from port "E" to port "F". When VSV is OFF, air from port "E" flows out through port "F". See Fig 2. If okay, go to step  49. If not okay, go to next step.
  46. Check vacuum hose between VSV for CCV and charcoal canister. Repair as necessary. If okay, go to next step.
  47. Check operation of VSV for CCV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If okay, go to next step. If not okay, replace VSV for CCV.
  48. Check for open and short in harness and connector between EFI or ECD relay and VSV for CCV, and VSV for CCV and ECM. Repair as necessary. If okay, check and replace ECM.
  49. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ENHANCED OBD2/ ACTIVE TEST mode on the hand-held tester. Select the item TANK BYPASS VSV/ALL in ACTIVE TEST and operate VSV for EVAP. Check the VSV operation when it is operated by the hand-held tester. When VSV is ON, air from port "E" flows out through port "F". When VSV is OFF, air does not flow from port "E" to port "F". See Fig 3. If okay, go to step  52. If not okay, go to next step.
  50. Check operation of VSV for pressure switching valve. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - LX470 article. If okay, go to next step. If not okay, replace VSV for pressure switching valve.
  51. Check for open and short in harness and connector between EFI or ECD relay and VSV for pressure switching valve, and VSV for pressure switching valve and ECM. Repair or replace harness or connector as necessary. If okay, check and replace ECM.
  52. Check whether hose close to fuel tank has been modified, and check whether there are signs of any accident near fuel tank or charcoal canister. See Fig 4. Repair as necessary. If okay, go to next step.
  53. Check vacuum hoses between vapor pressure sensor and fuel tank, and charcoal canister and VSV for pressure switching valve. Repair as necessary. If okay, go to next step.
  54. Check vacuum hoses. See Figure. Repair as necessary. If okay, go to next step.
  55. Remove the glove compartment door. Turn the ignition switch ON. Measure the voltage between terminals VC and E2 of the ECM connector. See Fig 5. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, check and replace ECM.
  56. Measure the voltage between terminals PTNK and E2 of the ECM connectors. Disconnect the vacuum hose from the vapor pressure sensor. Using the MITYVAC (hand-held vacuum pump) apply a vacuum of 1.18 in. Hg (30 mm Hg) , to the vapor pressure sensor. The vacuum applied to the vapor pressure sensor must be less than 19.7 in. Hg (500 mm Hg). See Fig 6. If voltage is 2.9-3.7 volts with vacuum hose disconnected, then drops to 0.5 volt or less, go to next step. If voltage is not to specification, check and replace ECM.
  57. Check for open and short in harness and connector between vapor pressure sensor and ECM. Repair as necessary. If okay, replace vapor pressure sensor.
scientia non olet · About LEMON Manuals