Circuit Description

PCM uses fuel level input from fuel level sensor to calculate expected vapor pressures within fuel system. 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 at least once per drive cycle.