GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0462: Fuel Level Sensor Circuit Low Voltage

Diagnostic Fault Information

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

P0464

P0463

P0461

Fuel Level Sensor Low Reference Circuit

--

P0463

1

P0464

P0463

P0461

1. Fuel Gage Inaccurate or Inoperative

Circuit Description

The fuel level sensor changes resistance based on 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 percent via the serial data circuit to the instrument panel cluster (IPC) in order to control the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.

Conditions for Running the DTC

    • The ignition is ON.
    • The system voltage is between 11-16 volts.

Conditions for Setting the DTC

    • The fuel level signal voltage is greater than 98 percent (less than 0.4 volt).
    • The above condition is present for greater than 10 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The check gages indicator illuminates.
    • The ECM records the operating conditions at the time the diagnostic 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 the 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

    •  Displays and Gages 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

Ignition ON, observe the scan tool Fuel Level Sensor parameter. The reading should be between 0.9-2.5 volts.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
  2. Ignition ON, verify that the scan tool Fuel Level Sensor parameter is greater than 4.5 volts.
  3. If less than 4.5 volts, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
  4. If all circuits test normal, test or replace the fuel level sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure

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