Circuit Description
WARNING: This page is about a different car, the 1996 Pontiac Firefly and 1996 Geo Metro. However, it is still accessible from the selected car via links, so may be relevant.
PCM uses fuel level input from fuel level sensor to calculate expected amount of vapor pressure in fuel tank. Vapor pressure information is used to determine if EVAP system is operating properly. Fuel level information is also used by PCM to determine if fuel level is too high or too low to accurately detect EVAP system failures. DTC P0461 will set when fuel level change from maximum to minimum is less than 2 gallons.