Circuit/System Testing

Ignition OFF, remove the fuel tank filler cap.
Ignition ON, observe the scan tool fuel tank pressure sensor voltage parameter. Verify the FTP sensor voltage parameter is less than 4 volts.
- If greater than 4 volts refer to DTC P0452 or P0453 .
Start the engine. With a scan tool seal the EVAP system using the EVAP purge seal function. Command the purge open to 20 percent. Seal the system at -8.00 in H20. Exit the system seal. Verify the FTP sensor pressure parameter decreases to 0 in H2O.
- If the scan tool FTP sensor parameter does not decrease, check for a blockage or restrictions in the EVAP vent hose, or replace the EVAP vent solenoid valve.