Circuit/System Description
WARNING: This page is about a different car, the 2008 Suzuki Swift +, 2008 Pontiac Wave, and 2008 Chevrolet Aveo. However, it is still accessible from the selected car via links, so may be relevant.
A restricted or blocked evaporative emission (EVAP) vent path is detected by the control module commanding the purge valve ON (open) and the vent valve ON (closed) allowing a vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the purge valve OFF (closed) and the vent valve OFF (open) while monitoring the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, DTC P0446 will set.
The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent valves.
| Control Module Command | EVAP Canister Purge Valve | EVAP Canister Vent Valve |
|---|---|---|
| ON | Open | Closed |
| OFF | Closed | Open |