DTC P0461: Fuel Tank Level Sensor Circuit Performance: Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2001 Saturn SW2, 2001 Saturn SL2, 2001 Saturn SL1, 2001 Saturn SL, and 2001 Saturn SC2. However, it is still accessible from the selected car via links, so may be relevant.
The PCM monitors resistance of fuel level sensor (tank sender) to calculate the amount of fuel in fuel tank, and provides voltage to tank sender through a resistor network and a return to PCM ground. When fuel level is high, sensor resistance is high and signal voltage is low. As fuel level decreases, sensor resistance decreases and signal voltage increases. PCM sends fuel level over Class II link to BCM. BCM averages signal over time, then sends a message to instrument panel to position gauge. DTC will set when signal voltage at PCM does not change a calibrated amount after vehicle has been driven a long distance.