For 1990-2009 cars

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 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 powertrain control module (PCM) measures the signal voltage from the fuel tank pressure sensor, which is a reduced value of the PCM 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 P0452 sets when the signal voltage at the PCM is below the calibrated voltage value.

### DTC Parameters

DTC P0452 will set if fuel tank pressure sensor voltage is less than 0.1 volts when:

• | The condition exists for longer than 3 seconds.

• | The ignition is ON.

DTC P0452 diagnostic runs continuously with ignition ON.

DTC P0452 is a type A DTC.

### Diagnostic Aids

Important: If DTC P1635 is also set, diagnose that DTC first.

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

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 signal voltage with the fuel cap off should read 1.3-1.7 volts, which represents atmospheric pressure 101 kPa (14.7 psi).