The EVAP vent valve allows fresh outside air to enter the canister during purge modes. The vent solenoid is closed only while the EVAP diagnostic runs. The voltage on the solenoid control circuit is monitored continuously. If the voltage remains above an upper threshold, this DTC will set.

DTC P0448 will set when:

P0448 is a (type B) DTC.

To locate an intermittent problem, use the scan tool to monitor the actual EVAP purge solenoid with engine running.

Wiggling wires while monitoring the EVAP purge solenoid may locate the area where a short to ground exists.