Where is the car fuel sensor located?
4 Answers
Car fuel sensor is located on the oil passage inside the main fuel tank of the engine, near the bottom. Its main function is to detect the liquid level inside the fuel tank and feed back to the vehicle's dashboard to determine the refueling time. The car fuel sensor can receive the measured information and convert it into output information according to the sensor's own rules, meeting the requirements of information transmission, processing, storage, display, recording and control. There are many types of fuel level sensors, such as capacitive, electronic, etc. Different designs have different shapes and working principles. The old pendulum-type float is a hollow ball that can float on the surface of the oil layer, using the lever principle. The other end of the float is a potentiometer. The amount of oil determines the height of the float, and the potentiometer at the other end will reach different potentials according to the oil level, which is displayed on the dashboard. The sensing part of the capacitive fuel level sensor is a coaxial container. When oil enters the container, it causes a change in the capacitance between the sensor shell and the sensing electrode. This change is converted by the circuit and accurately compensated for linearity and temperature, outputting a 420mA standard signal to the display instrument. Electronic types can be divided into resistance, voltage, frequency and other output forms according to different output signals.
The fuel level sensor is submerged inside the fuel tank, installed at the top position inside the tank. This float is directly connected to the fuel pump inside the tank, floating on the gasoline like a small fishing rod. When you start the car, it detects the fuel level through the up and down movement of the float, then transmits the data to the dashboard. The position varies slightly depending on the vehicle type - in sedans, it's usually hidden under the rear seats, requiring you to lift the seat cushion to see the fuel tank cover panel; while SUVs with higher ground clearance have the fuel tank located in the middle undercarriage area, requiring the vehicle to be lifted for access. If this component fails, it's troublesome - the fuel gauge needle on the dashboard will dance erratically. Once when I replaced it, it cost me over 400 bucks and required draining half a tank of fuel.
This thing is directly mounted on the fuel pump assembly, with the entire assembly submerged in the fuel tank. As for its location, the fuel tank is its home. Different vehicle models have differently shaped fuel tanks, so the sensor adapts accordingly. In sedans, you can usually access it through the maintenance port under the rear seat—just lift the cover plate. For SUVs, the fuel tank is located slightly towards the rear in the middle of the chassis. If you notice your fuel gauge acting erratically while driving, with the needle jumping up and down unpredictably, it's likely due to oil sludge buildup on the sensor surface or a deformed/stuck float arm. During repairs, the fuel must be completely drained. Mechanics dread replacing this part the most—not only do they end up with gasoline all over their hands, but it's also easy to dirty the car's interior.
It's stuck on the fuel pump inside the fuel tank, with varying positions depending on the vehicle. For sedans, the fuel tank is mostly under the rear seat, where you can find a round metal cover by lifting the cushion. For pickups and SUVs, the fuel tank is located underneath the vehicle. The sensor uses a plastic float that floats on the gasoline, connected to a resistor. As the fuel level changes, the resistance value varies, giving the reading on the dashboard. I just replaced the sensor last month because the fuel gauge always showed empty but I could still drive a hundred kilometers. The mechanic said moisture in the fuel tank can cause rust and jam the float, advising not to wait until the fuel light comes on to refuel.
