P0452

Diagnostic Chart Part 1:

Diagnostic Chart Part 2:

Schematic:

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 (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 high when the pressure in the fuel tank is low (vacuum) and will decrease as the pressure in the tank increases. DTC P0452 will set if the fuel tank pressure sensor signal voltage at the ECM is below the calibrated voltage value.

DTC PARAMETERS
DTC P0452 will set if fuel tank pressure sensor signal voltage is less than 0.15 volts when:
^ Condition exists for longer than 10 seconds
^ Ignition is On

DTC P0452 diagnostic runs continuously with ignition On.

NOTE: Once the fuel tank pressure sensor signal voltage drops below 0.15 volts, the voltage level must exceed 0.35 volts in order to pass the diagnostic.

P0452 is a type B DTC.

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor FTP SENSOR voltage with ignition On, engine Off. Wiggling wires while watching for a change in FTP SENSOR voltage may locate the area where an open or short to ground in the wiring may exist.

FTP SENSOR on Scan tool should read between 1.40 and 1.60 volts with ignition On, engine Off and fuel cap removed. This represents atmospheric pressure or 0 inches of vacuum.

Circuit 2760 (MAF sensor), circuit 2709 (AC pressure/fuel tank pressure sensor) and circuit 1164 (APP sensor 1) share the same 5 volt reference supply (5 volt Ref-A).

The fuel level sensors and fuel tank pressure sensor share the same sensor return circuit 2759.

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.