DTC P0451: Fuel Tank Pressure Sensor Performance: Description

The DTC P0451 Fuel Tank Pressure (FTP) Sensor Performance diagnostic checks the accuracy of the FTP sensor signal. The Evaporative Emission (EVAP) control system prevents the emission of the fuel vapors. The fuel vapor generated in the fuel tank while driving or idling enters the EVAP canister where a charcoal element absorbs and stores the fuel vapor. When certain engine operating conditions are met the Powertrain Control Module (PCM) purges the EVAP canister of stored vapors by turning ON the EVAP canister purge valve.

Emissions laws require that the PCM detect any leakage within the EVAP system. The PCM monitors the EVAP system for leaks by controlling and observing the vapor pressures in the EVAP system. The FTP sensor is used to detect any unexpected pressure in the EVAP system. The PCM supplies a 5-volt reference and an electrical ground to the FTP sensor. The FTP sensor contains a silicone based chip that changes electrical resistance when pressure is applied. The sensor converts the positive or the negative pressure into an electrical signal and sends the signal to the PCM.