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Error Code P0463 is defined as Fuel Level Sensor Circuit High Input.
This error code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made from 1996 up to the present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
The fuel level sensor (also known as sender) is an essential component of the fuel pump module and located in the fuel tank. This component can’t be replaced without replacing the pump module, though there are some exceptions. Attached to the arm is a float that travels with a resistor grounded to the tank, frame or a dedicated ground circuit. The sender receives a supplied voltage, and the ground path changes according to the level of fuel. The amount of voltage depends on the system, but in many times it’s around 5V.
As the fuel level changes, the float moves the arm, changing the resistance to ground which varies the voltage signal. This signal will either go straight to the fuel pump computer module, or to the instrument cluster module. Depending on the vehicle’s system, the fuel pump computer module may only monitor the resistance to ground, and then relay the fuel level information to the instrument panel. If the fuel level signal in the fuel pump module (or PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes), or instrument cluster module) is set above 5V for a specific amount of time, the module that monitors the fuel level circuit will record it as an error, prompting the PCM to register the Error Code P0463.
Other related fuel level sensor circuit trouble codes include:
- Error Code P0460 Fuel Level Sensor Circuit Malfunction
- Error Code P0461 Fuel Level Sensor Circuit Range/Performance
- Error Code P0462 Fuel Level Sensor Circuit Low Input
- Error Code P0464 Fuel Level Sensor Circuit Intermittent
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. Other common symptoms include:
- Fluctuating or inaccurate fuel gauge
- Fuel light or alarm activated, indicating low fuel level
There are many possible causes for this code to happen, such as:
- Defective fuel level sensor
- Defective fuel level sensor circuit
- Damaged fuel level sensor float in the gas tank
- Damage or corrosion inside the gas tank
- Defective PCM (rare)
How to Check
As with many error codes, technicians start their diagnosis of this code using OBD-II scanner to scan and verify the code. Then, they will clear the code, duplicate the circumstances when the code first showed up, and then take the vehicle for a test drive. While doing so, they will monitor the fuel gauge and the data they receive to determine whether the problem was erratic or steady. This is also to determine whether there is more or less fuel in the tank than there actually is.
After the test drive, the technician will then work through the problem systematically. They will start by inspecting the fuel tank and the wiring harness and look for signs of damage to the tank.
Then, they will proceed on checking for missing ground strap, or rusty ground where the fuel is grounded to the frame. They also check for damages in the wiring harness connector.
Also, they may perform a voltage drop test on the ground circuit to determine if there is a high resistance path in the ground circuit. They do this by connecting a voltmeter to the battery ground post, while the other to the fuel level sensor ground at the tank. Then they turn the key on to run the engine. Ideally, there should be 100millivolts or less (.1V). Anything close to 1V means there’s a problem.
How to Fix
Repairs for this code are pretty easy and straightforward. Obviously, defective components must be repaired, if not replaced. Common repairs include:
- Repair or replacement of the fuel tank
- Repair or replacement of the fuel level sensor float
- Repair, replacement, or clean the fuel level sensor ground as needed
- Replacement of the wiring harness for the fuel level sensor
- Tightening a loose connection in the fuel level sensor circuit
Though Error Code P0463 does not cause immediate danger to the vehicle, it can be dangerous if your vehicle stalls in traffic. Or at least very inconvenient, as you can run out of gas and can be stranded away from home, or places with poor conditions, if you are unable to tell how much gas you have.