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 P0461: Fuel Level Sensor 1 Performance

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, P0464

P0463

P0461

Fuel Level Sensor Low Reference Circuit

--

P0463, P0464

P0463

P0461

Circuit/System Description

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

This diagnostic tests for a lower than normal fuel level sender signal.

Conditions for Running the DTC

The engine is ON.

Conditions for Setting the DTC

The ECM detects a change is fuel level less than 10 liters (1.3 gallons) over a distance of 241.4 km (150 miles).

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 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.

Diagnostic Aids

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.

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  Engine Controls Schematics

Connector End View Reference

    •  Displays and Gages Connector End Views
    •  Engine Control Module Connector End Views

Description and Operation

    •  Instrument Cluster Description and Operation
    •  Fuel System Description
    •  Engine Control Module Description

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing

  1. Ignition OFF, remove the fuel level senders and verify that there is no obstructions interfering with the fuel level senders.
  2. If interference is present, remove the obstruction.
  3. If no interference is present, replace the fuel level senders.

Component Testing

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

If the resistance does not move smoothly across the specified range, replace the fuel level sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Primary Fuel Tank Module Replacement
    •  Secondary Fuel Tank Module Replacement
    •  Control Module References for ECM replacement, setup, and programming