Fuel Tank Pressure Sensor: Description and Operation

Fuel Tank Pressure Sensor

The Fuel Tank Pressure sensor is used to detect small leaks in the evaporative emission system. The fuel tank pressure sensor is a three wire strain gauge sensor much like the MAP sensor. However, this sensor has very different electrical characteristics due to the pressure differential design. The sensor measures the difference between the air pressure (or vacuum) in the fuel tank and the outside air pressure. The sensor mounts at the top of the fuel tank. A three wire electrical harness connects it to the Powertrain Control Module (PCM). The PCM supplies a 5.0 volt reference voltage and a ground to the sensor. The sensor will return a voltage between 0.1 and 4.9 volts. When the air pressure in the fuel tank is equal to the outside air pressure, such as when the fuel cap is removed, the output voltage of the sensor will be 1.3 to 1.7 volts.