Engine Oil Level Warning Sensor
WARNING: This page is about a different car, the 2003 Lexus GS 430, 2003 Lexus GS 300, 2002 Lexus GS 430, and 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
Check that continuity exists between terminals with the switch to below 104°F (40°C), warning switch ON. See Fig 1. Heat the switch to above 104°F (40°C) in an oil bath. Check that there is continuity between terminals with the switch ON (float up). Check that there is no continuity between terminals with the switch OFF (float down). If operation is not as specified, replace the switch.