Fuel Tank Pressure Sensor: Description and Operation

Fuel Tank Pressure Sensor:

The Fuel Tank Pressure (FTP) sensor is located on top of the fuel sender assembly, located on top of the fuel tank. The FTP sensor is used solely for EVAP leak diagnostics, but also aids in disabling purge mode if too much vacuum is present in the fuel tank during normal purge operation (if vent system is blocked). This will prevent the fuel tank from possible damage.

The FTP sensor is a transducer that changes resistance based on the difference between the fuel vapor pressure inside the fuel tank and the outside air pressure. The ECM supplies the sensor direct 5 volts and a reference return circuit. Normal signal voltage readings with the fuel cap removed should be between 2.35 and 2.85 volts, which represents atmospheric pressure. As pressure in the fuel tank increases above atmospheric, the signal voltage will increase above the atmospheric voltage reading As the pressure in the fuel tank drops below atmospheric (vacuum), the signal voltage will fall below the atmospheric voltage reading. It is important to check the validity of the FTP sensor reading when diagnosing any EVAP system leak DTC, since the ECM uses the FTP sensor in all of its EVAP leak diagnostic measurements. A skewed sensor signal value may falsely set an EVAP leak DTC.