The DTC code P0497 OBDII is configured when the PCM (Powertrain Control Module) finds a purge flow rate of the EVAP (Evaporative Emissions Control System) system which is lower than expected.
The EVAP system captures and contains the fuel vapors, then it sends them to the engine to be burned before they escape into the atmosphere. This system is sealed by the fuel filler cap, a venting valve that allows air to enter so that the fuel vapors are displaced to the engine by a purge valve that allows the vapors to pass into the engine.
The fuel vapors remain in the coal can until a certain pressure is reached which has already been established by the manufacturer. When pressure is reached, the PCM orders the opening of the ventilation valve on or near the carbon canister to bring in the fresh air, at which time the fuel vapors are sucked by the engine out of the activated carbon filter. The actual flow rate with the expected flow rate is compared by the PCM to control both the opening and closing of the bleed valve, thus allowing the flow rate values to match. If the PCM determines that the flow rate required to purge the system is less than expected, this code is set and the Check Engine light is illuminated.