Fuel Tank Pressure Sensor: Description and Operation

The fuel tank pressure sensor mounts to the sending unit at the top of the fuel tank. The fuel tank pressure sensor measures the pressure changes within the Evaporative Emission (EVAP) System. The fuel tank pressure sensor has a 5.0 volt reference circuit, a ground circuit, and a signal circuit.

The fuel tank pressure sensor contains a diaphragm that changes resistance based on pressure. When the EVAP system pressure is low, during purge, the sensor output voltage is low. When the system pressure is high, the sensor output voltage is high. The signal from this sensor provides feedback to the ECM on the EVAP system operation. The ECMs programming contains information on expected EVAP system behavior under various operating conditions. The ECM monitors the EVAP system pressure. If the fuel tank pressure sensor signal is outside of the normal operating range, then DTC P0450-Fuel Tank Pressure Sensor Circuit will set.

If the fuel tank pressure sensor signal differs from an expected result during an EVAP system test, caused by either a sensor problem or an actual EVAP system problem, the following DTCs can set:
^ DTC P0440 - EVAP System Performance
^ DTC P0442- Evaporative Emission (EVAP) System Small Leak Detected
^ DTC P0455 - Evaporative Emission (EVAP) System Leak Detected