importrix

From time to time error P1422 (Fuel Tank -- Small Leak) pops up on my ECU. The fuel cap closes tight, O ring looks healthy, yet I often smell petrol in the garage. the tubes that connect to what looks like a vapor canister are attached tight, they are dry and as much as I can tell they don't smell. I don't believe this canister has ever been serviced on this 2006 RX400h. Perhaps the charcoal needs to be replaced in it? Do you guys know the service cycle and procedure of the fuel vapor canister? Or is it something else? Perhaps the fuel cap?
Please advise.