The purge valve is usually located near the evap canister. Look for a small hose that connects to the throttle body close to the throttle valve. The other end of that hose connects to the purge valve.
As far as the vent valve, from what I see your car has these evap valves
- purge control solenoid valve
- over-fill limiter aka 2 way check valve (in the line between the fuel check valve and the canister)
- fuel check valve (in the evap line between fuel tank and the 2 way check valve)
- leveling pipe (another overfill limiter gadget), connects to the re-fueling tube.
- roll-over & orvr valves (both near fuel tank)
Both p0456 & 0442 indicate a small evap leak is detected, not specific to any particular part of the evap system. could be anywhere in other words. evap vent problems could be caused by a plugged vent filter btw, canister ass’y. A problem with the fuel tank pressure sensor could confuse the computer, making it think there’s a leak when there isn’t.