1181041B02 is the part number. The service manual mentions that you have to change the gasket if you're "poking" around the area (part no. 1181241B00). I bought them from amayama (the delivery time is about 2-3 weeks and they're genuine).
Some people just clean the valve with carb spray cleaner...
On diesel models the filter is somewhere in the engine bay and is replaceable, on petrol engines is integrated in the fuel pump and is inside the fuel tank.