DTC P0464: Fuel Gauge Sending Unit Circuit, Slosh Check: Condition
WARNING: This page is about a different car, the 2002 Mazda Protege5 and 2002 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.
DTC is set when fuel gauge sending unit input voltage changes excessively for 14 seconds when vehicle is stopped and engine is running. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possibly caused by fuel gauge sending unit malfunction.