Miles?

Original O2 sensors?


Classic failure mode for cat efficiency is for a motor to run very rich, which 'swamps' the O2 sensors and causes them to think the cat is bad. Saw a TON of cat replacements on the S62s for this, as those motors had aggressive tuning.


I dont know where those are on your car. Somewhere underneath. I mean get a jack and some wrenches and have at it. Honestly if the O2s are old, replace them all.


But I am not sure o2s are the cause of your driveability issues. A air leak in the intake... or a bad vanos solenoid...or something impacting timing/advance...could all cause rich running, with sluggish responses.


Can you pull your AFRs? (Fuel rations, long and short term fuel trims)? Invest the 150 in a decent reader, it may be worth the effort...


GL