Sensor issue ?

I have a PO456 & a PO440 code I took it to a mechanic where they ran a smoke test and said they didn’t see any leaks at all . Mechanic said it might be a evap detection sensor ?

‼️ i just wanted to know if anyone has replaced a sensor for this issue what sensor was it and how much did it run you ? Mechanic also said purge valve and gas cap are fine as well