I have the same model and year and am now on the third Cat and valve cleanand Lexus say this is normal.... dont think so !! this has been a rubbish car and LEXUS HAVE BEEN RUBBISH AS WELL!!
who else has had three catalytic convertors on a 57 plate is220d !..... not happy at all especially as Lexus say this is normal and that they wont contribute to ANY repair costs !!!