Diagnostic Aids

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

A short to ground causing the EVAP vent solenoid ON will cause the vent valve to close. This will cause DTC P0446 to set.
ECM uses the FTP sensor to detect the amount of vacuum pulled on the EVAP system during the leak diagnostic tests. Ensure that the fuel pressure sensor is not skewed by verifying the FTP sensor on the scan tool is 1.30-1.70 volts with the ignition on and fuel cap removed.
Inspect for cause of blocked EVAP vent solenoid or a stuck valve. Inspect for plugged, kinked or pinched vent hose. Inspect for a restricted EVAP canister.