Circuit Description

PCM uses fuel level input from fuel tank 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 one gallon even though volume of intake air is calculated to be greater than 660 kg.

When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. PCM will record operating conditions at time of failure and store information in freeze frame buffer.