Circuit/System Description

The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sensor in order to determine the 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 percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via GMLAN serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information is also used for evaporative emission (EVAP) and other OBD diagnostics diagnostics.

This diagnostic tests for an intermittent fuel level sensor signal. If a change in fuel level is detected, DTC P0442 is aborted due to a possible refueling event. If refueling is confirmed, the test for DTC P0464 is considered a pass. The refueling event test must pass two out of three times, otherwise, the DTC P0464 will set indicating an intermittent signal problem.