Vapor Pressure Sensor (Highlander)
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2003 Toyota Tundra, 2003 Toyota Tacoma, 2003 Toyota Sienna, 2003 Toyota Sequoia, and 2003 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
For testing of vapor pressure sensor, see Fig 1 and Fig 2 . Before replacing ECM, check ECM connectors and ground circuits. See ENGINE CONTROL MODULE POWER & GROUND CIRCUITS under COMPUTERIZED ENGINE CONTROLS.