Fuel Tank Pressure

The scan tool displays 0 to 64 in. H2O or 0 to 119.5 mm Hg. The signal from the fuel tank pressure sensor is monitored by the PCM to verify that the evaporative emissions control system is operating correctly and leaks are not present. Fuel Tank Pressure level is used extensively for [1][2]EVAP purge control and EVAP system diagnostics.