Fuel Tank Pressure Sensor

Disconnect fuel tank pressure sensor electrical connector. Turn ignition on with engine off. Using a DVOM, measure voltage between fuel tank pressure sensor harness connector 5-volt reference circuit and ground circuit. See WIRING DIAGRAMS article. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, diagnose problem using DTC P0450 test procedures. See TESTS W/CODES article.
Using a DVOM, measure voltage between ground and fuel tank pressure sensor harness connector input circuit. See WIRING DIAGRAMS article. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, diagnose problem using DTC P0450 test procedures. See TESTS W/CODES article.
Turn ignition off. Reconnect fuel tank pressure sensor electrical connector. Disconnect vacuum hose from fuel tank pressure sensor. Connect a hand-held vacuum/pressure pump to fuel tank pressure sensor. Set DVOM to DC scale. Using DVOM, backprobe fuel tank pressure sensor 5-volt reference circuit and ground circuit of PCM. See WIRING DIAGRAMS article. Measure voltage while applying and releasing vacuum as follows:
- Apply .59 in. Hg vacuum to fuel tank pressure sensor. Voltage should be 1.3-2.1 volts.
- Release vacuum from fuel tank pressure sensor. Voltage should be 3.0-3.6 volts.
- Apply .22 psi (.015 kg/cm² ) pressure to fuel tank pressure sensor. Voltage should be 4.2-4.8 volts.

If voltage readings are as specified, fuel tank pressure sensor is okay. If any voltage reading is not as specified, replace fuel tank pressure sensor.

NOTE: Fuel tank pressure control valve will not allow air to flow from fuel tank port to canister port until tank port side pressure is more than .5 psi (.035 kg/cm² ).