Technical Description of OBD-II Trouble Code
High Input in Fuel Level Sensor Circuit
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code, which means it applies to vehicles equipped with OBD-II. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The fuel level sensor (sender) is typically located in the fuel tank and is usually integrated with the fuel pump module. In most cases, the fuel pump module needs to be replaced in order to replace the fuel level sensor, although there are exceptions. The sensor consists of a float attached to an arm that moves along a resistor. The resistor is either grounded to the tank or frame, or it has a dedicated ground circuit. The sender receives voltage and the ground path changes based on the fuel level. The amount of voltage supplied depends on the system, but 5 volts is common.
As the fuel level changes, the float moves the arm, which alters the resistance to ground and consequently varies the voltage signal. This signal may be sent to a fuel pump computer module or directly to the instrument cluster module. Depending on the system, the fuel pump computer module may only monitor the resistance to ground and then transmit the fuel level information to the instrument panel. If the fuel level signal to the fuel pump module (or instrument cluster module or PCM) exceeds 5 volts for a specific duration, the module monitoring the fuel level circuit will record this fault code.
Other related trouble codes for the fuel level sensor circuit include:
Symptoms
The symptoms of a P0463 DTC may include:
Causes
Possible causes of a P0463 code include:
Possible Solutions
Fuel pump senders typically last the lifespan of the fuel pump. Therefore, if you have this code, visually inspect the fuel tank and wiring harness. Look for any damage to the tank that may indicate an impact that could have damaged the fuel pump or sender. Check for a missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Examine the wiring harness connector for any damage. Repair as necessary. Determine the type of system you have and verify that there is voltage present at the fuel level sensor in the fuel pump wiring harness. If there is no voltage, repair the open or short in the wiring.
You can perform a voltage drop test on the ground circuit to determine if there is a high resistance path in the ground circuit. Use a voltmeter to connect one lead to the battery ground post and the other lead to the fuel level sensor ground at the tank. Turn the key on (preferably with the engine running). Ideally, the voltage drop should be 100 millivolts or less (0.1 volts). A voltage close to 1 volt indicates a current problem or a developing problem. Repair or clean the fuel level sensor ground as needed. It is possible that the instrument cluster has failed internally or on the printed circuit board (if applicable). These are difficult for non-professionals to test. However, if you have access to a wiring diagram, you may be able to remove the cluster and identify any damaged circuits on the printed circuit board. Otherwise, you will need a scan tool that can communicate with the instrument cluster.
A simple way to test the fuel level circuit is to provide a good ground to the fuel level sensor at the fuel tank connector. With the key on, the fuel gauge should move to one extreme or the other. Removing the ground path completely should cause the gauge to move in the opposite direction. If the gauge responds, it indicates that the wiring supplying voltage and ground to the fuel level sensor is functioning properly and that the instrument cluster is likely okay. The most likely culprit would be the fuel level sensor itself. Accessing the fuel pump module in the tank may require removing the fuel tank. A failure in the PCM or BCM (Body Control Module) is possible but highly unlikely. Do not suspect these components as the first cause.
