Conditions for Running the DTC

WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The engine speed is more than 80 RPM.
The ignition 1 voltage is between 10.5-18 volts.
The ECM has commanded the EVAP canister vent valve ON and OFF at least once during the ignition cycle.
DTC P0498 runs continuously once the above conditions have been met.