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, the 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 low when the pressure in the fuel tank is low (vacuum) and will increase as the pressure in the tank increases. DTC P0453 will set if the fuel tank pressure sensor signal voltage at the ECM is above the calibrated voltage value.

DTC P0453 will set if the fuel tank pressure sensor signal voltage is greater than 4.9 volts when:

DTC P0453 diagnostic runs continuously with the ignition ON.

DTC P0453 is a type B DTC.

To locate an intermittent problem, use the scan tool to monitor FUEL TANK PRESS. SENSOR voltage with the ignition ON and the engine OFF. Wiggling the wires while watching for a change in FUEL TANK PRESS. SENSOR voltage may locate the area where an open or short to voltage in the wiring may exist.

FUEL TANK PRESS. SENSOR on the scan tool should read between 2.35-2.85 volts with the ignition ON and the engine OFF and the fuel cap removed. This represents atmospheric pressure or 0 inches of vacuum.

Circuit 416 (CMP/EGR/MAF/MAP sensor), circuit 2709 (A/C pressure/fuel tank pressure sensor), and circuit 1164 (APP sensor 1) share the same 5-volt reference supply, 5-volt Ref-A.

Important: Inaccurate readings will occur if resistance measurements are taken on a fuel tank pressure sensor. The fuel tank pressure sensor contains an internal amplifier circuit that requires applied voltage to function properly.

The A/C pressure sensor, APP sensor 2, fuel level sensor and fuel tank pressure sensor share the same sensor return circuit 2759.