Circuit Description

The fuel level sensor changes resistance based on the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sensor in order to determine fuel level. When the fuel tank is full, the sensor resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the total remaining fuel percent in the tank. The ECM sends the fuel level message via the class 2 serial data circuit to the instrument panel cluster (IPC) for the fuel gage display. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.

This diagnostic tests for an intermittent fuel level sensor signal. If a change in fuel level is detected, the engine-off natural vacuum small leak test DTC P0442 is aborted due to a refueling event. Before aborting DTC P0442 a refueling event test is executed to confirm that a refueling event has occurred. If refueling is confirmed, the test is considered a pass. Otherwise, the DTC P0464 sets indicating an intermittent signal problem.