Canister Vent Restriction Test

After the small leak test has passed, a vacuum is retained in the evaporative emission (EVAP) system. The control module tests for a restricted vent path by commanding the purge valve OFF closed and the vent valve OFF open. The fuel tank pressure (FTP) sensor is monitored for a decrease in EVAP system vacuum. If the vacuum does not decrease to near 0 inch H2O in a calibrated time, DTC P2422 will set.