Technical Description of OBD-II Trouble Code
Intermittent Circuit Issue with Fuel Level Sensor
What does that signify?
This generic powertrain/engine diagnostic trouble code typically applies to all OBDII equipped engines, but is more commonly found in certain Hyundai, Infiniti, Isuzu, Kia, Mazda, Mercedes Benz, Nissan, and Subaru vehicles.
The Fuel Level Sensor (FLS) is typically located in the fuel tank, usually in the top part of the fuel tank / fuel pump module. The FLS converts the mechanical fuel level into an electrical signal for the Powertrain Control Module (PCM). Usually, the PCM will then communicate this information to other controllers using the vehicle’s data communication bus.
The PCM receives this voltage signal to determine the amount of fuel in the fuel tank, monitoring fuel usage and calculating fuel economy. This code is triggered if this input does not match the normal operating voltages stored in the PCM’s memory, even for a brief moment, as demonstrated by this diagnostic trouble code. It also checks the voltage signal from the FLS sensor to verify its accuracy during initial Key On.
P0464 could be triggered due to mechanical (such as incorrect fuel level rationality; refueling the vehicle with the ignition switch “on” or even with the engine running can cause this. Rapid changes in fuel level that are not normal) or electrical (FLS sensor circuit) issues. These factors should not be overlooked during the troubleshooting stage, especially when dealing with an intermittent problem.
Troubleshooting steps may vary depending on the manufacturer, type of FLS sensor, and wire colors.
Related fuel level sensor circuit trouble codes include:
Severity & Symptoms
The severity depends on the cause of the failure. If it is a mechanical failure, it can be severe. If it is an electrical failure, it is not as severe since the PCM can compensate for it. The compensation usually results in the fuel gauge always reading Empty or Full.
Symptoms of a P0464 engine code may include:
Potential Causes
The typical causes for this code to be triggered are:
Diagnostic and Repair Procedures
A good starting point is always to search for any technical service bulletins (TSB) related to your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogram available to address this issue, so it is worth checking before going down a potentially lengthy and incorrect path.
Next, locate the Fuel Level Sensor (FLS) in your specific vehicle. This sensor is usually found mounted in the fuel tank or possibly even in the top part of the fuel tank / fuel pump module. Once located, visually inspect the connector and wiring. Look for any signs of scraping, rubbing, bare wires, burn spots, or melted plastic. Disconnect the connector and carefully examine the terminals (the metal parts) inside the connector. Check for any signs of burning or corrosion indicated by a green tint. If cleaning of the terminals is necessary, use electrical contact cleaner and a plastic bristle brush. Allow them to dry and apply electrical grease to the contact points.
If you have a scan tool, clear the diagnostic trouble codes from memory and see if the P0464 code returns. If it does not, then the issue was most likely related to the connections.
This is the most common area of concern for this code, as the fuel tank connections are prone to corrosion issues.
If the P0464 code does return, further testing of the FLS sensor and its associated circuits will be necessary. With the Key Off, disconnect the electrical connector at the FLS sensor. Connect a Digital Voltmeter (DVOM) black lead to the ground or low reference terminal at the FLS sensor wiring harness connector. Connect the red lead of the Digital Voltmeter to the signal terminal at the FLS sensor wiring harness connector. Turn the Key On but keep the Engine Off. Check the manufacturer’s specifications; the voltmeter should read either 12 volts or 5 volts. Wiggle the connections to see if there are any changes. If the voltage is incorrect, repair the power or ground wire, or replace the PCM.
If the previous test passed, connect one lead of an ohmmeter to the signal terminal at the FLS sensor and the other lead to the ground or low reference terminal at the sensor. The ohmmeter reading should not be zero ohms nor should it be infinite. Check the manufacturer’s specifications for the resistance of the sensor to accurately test the resistance in relation to the fuel level (for example, 1/2 tank of fuel might read 80 ohms). Wiggle the connector at the Fuel Level Sensor while monitoring the resistance. If the ohmmeter readings do not pass, replace the FLS.
If all previous tests have passed and you continue to receive a P0464 code, it is most likely indicating a failed FLS sensor. However, a failed PCM cannot be ruled out until the FLS sensor has been replaced. If unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed or calibrated to the vehicle in order to be installed correctly.
