P0446 BMW code. Gas cap? vapor recovery system??

Question

have changed O2 sensor b1 s2 and gas cap. but P0446 code has returned again.

Answer 1

check all evaporated systems. .for leaks very sensitive will set code every time and stay on ..possible causes are bad connects on lines or rubber has rotted and will not let the vapors go to engine. .most likely somewhere theres a break somewhere may be difficult to find with out smoke machine. .small or very small evap leaks are common and set codes ..gas cap o ring to ..but u did that ..good luck