P0464

Symptoms

• Erratic or flickering fuel gauge (may show full or empty regardless of actual level)
• incorrect fuel-level readout
• intermittent low-fuel warning
• check engine light illuminated.

Probable causes

• Burnt
• damaged
• shorted or corroded wiring and/or connectors (fuel tank connections are prone to corrosion - most common cause)
• defective fuel level sender unit
• fuel residue or water contamination on the sender's resistance coil causing unstable voltage
• poor ground path at the sensor or within the instrument cluster
• communication fault in the instrument cluster or BCM.

Diagnostic steps

1. Scan the vehicle, record freeze frame data, clear the code and retest - if it does not return, the fault was most likely in the connections.
2. Inspect the wiring and connectors at the fuel tank / sender unit for damage, chafing and corrosion.
3. With the key off, disconnect the fuel level sensor connector; connect a digital voltmeter between the ground/low-reference terminal and the signal terminal of the harness connector, turn the key on (engine off) and verify the reference voltage against manufacturer specification (12 volts or 5 volts depending on application).
4. Monitor the sensor signal voltage with the vehicle stationary - fluctuations greater than +/-0.5 V suggest wiring or sensor issues.
5. Check the sensor ground path, including behavior under changing electrical loads (e.g. headlights on).
6. If wiring and grounds test good, replace the fuel level sender unit (often part of the fuel pump module).
7. Clear codes and verify the gauge reads correctly.