98 m3 below threshold cal 4-6 code...what should I do?
Hey guys I am new m3 owner and my cel came on and i read it with my peak reader and the only code that comes back is 'catalyst below threshold cyl #4-6'. I am looking what should I do first. I have read to replace pre cat sensor but I have also seen to replace the post cat sensor, what do you think? I believe the original o2 sensors are still in it and it has 82000 miles on it. Thanks for the help, cheers.