DTC P0451: EVAP Fuel Tank Pressure Sensor Circuit Performance: Description

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The Evaporative Emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The function of the Fuel Tank Pressure (FTP) sensor is solely for EVAP leak diagnostics. The fuel tank pressure sensor is a transducer that varies resistance according to changes in fuel tank pressure (difference between fuel tank and outside air pressure). The ECM measures the signal voltage from the fuel tank pressure sensor, which is a reduced value of the ECM 5-volt reference. The signal voltage will read high when the pressure in the fuel tank is low (vacuum) and will decrease as the pressure in the tank increases. DTC P0451 will set if the fuel tank pressure sensor signal voltage at the ECM is above or below a calibrated voltage value considered unrational.