Circuit/System Description
WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. The vacuum should decrease to near 0 inch H2O in a calibrated period of time.
DTC P0446
| FTP Sensor Signal Voltage | Fuel Tank Pressure |
|---|---|
| Low, Approximately 1.5V or less | Positive Pressure |
| High, Approximately 1.5V or more | Negative Pressure/Vacuum |