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

This diagnostic test for an intermittent fuel level sender signal. If a change in fuel level is detected DTC P0442 is aborted due to a refueling event. A refueling event test is executed to confirm that a refueling event has occurred. If refueling is confirmed, the test is considered passing. Otherwise, the DTC will set indicating an intermittent signal problem.

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Schematic Reference

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition OFF, disconnect the harness connector at the fuel level sensors.
2. Ignition OFF, test for less than 1 ohm of resistance between terminal C of the primary fuel level sensor and terminal B of the secondary fuel level sensor.

⇒	If greater than 1 ohm, test the circuit between terminal C of the primary fuel level sensor and terminal B of the secondary fuel level sensor for an open/high resistance.

3. Ignition OFF, Install a signal generator and instrument panel tester between the signal circuit and the low reference circuit.
4. Ignition ON, vary the resistance on the signal generator from 40 to 250 ohms. Verify that the scan tool Fuel Level parameter displays the correct fuel level.

⇒	If the fuel level is incorrect, test the signal circuit and the low reference circuit for an open/high resistance. If the circuits test normal, replace the ECM/PCM.

5. If all circuits test normal, test or replace the appropriate fuel level sensor.

Measure the resistance of the float arm of the fuel level sender while moving the float arm between 40-250 ohms.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.