GM Service Manual Online
For 1990-2009 cars only

DTC Descriptor

DTC P0462: Fuel Level Sensor Circuit Low Voltage

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Fuel Level Sensor Reference Voltage Circuit

P0462

--

P0461

Fuel Level Sensor Signal Circuit

P0462

P0463

1

P0463

P0461

Fuel Level Sensor Low Reference Circuit

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P0463

1

P0463

P0461

1. Fuel Gage Inaccurate or Inoperative

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 misfire and evaporative emission (EVAP) diagnostics.

Conditions for Running the DTC

    • The ignition is ON, with the engine running.
    • The system voltage is between 9-16 volts.

Conditions for Setting the DTC

    • The sender output is less than 0.39 volt.
    • The above condition is present for greater than 30 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The low fuel indicator illuminates.
    • The ECM records the operating conditions at the time that the diagnostic test fails. The ECM displays the failure information in the Failure Records on the scan tool

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction-free warm-up cycles.
    • The ECM receives a clear code command from the scan tool.

Reference Information

Fuel Level Specifications

Fuel Level Specifications

Schematic Reference

    •  Instrument Cluster Schematics
    •  Engine Controls Schematics

Connector End View Reference

    •  Instrument Panel, Gages, and Console Connector End Views
    •  Engine Control Module Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the ECM EVAP Data List should indicate a value at or greater than 98 percent.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
  2. Ignition ON, with the scan tool observe the Fuel Tank Level Remaining parameter. Verify the Fuel Tank Level remaining parameter is 4 percent or less.
  3. If the Fuel Tank Level Remaining parameter indicates a value greater than 4 percent, test the fuel level sensor signal circuit for a short to ground. If the fuel level sensor circuit tests normal, replace the ECM.
  4. If all circuits tests normal, test or replace the fuel level sensor.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Level Sensor Replacement
    •  Control Module References for the ECM replacement, setup and programming