Am in the process of minimizing fuel trim differences between the left and right cylinders of my ML 55 AMG 2001 250 kkm. Those differences used to be significant, but now I got them down to just a few percent.
The only probable reason for those differences that remains is imo the right front O2 sensor which sporadically even generates some sort of error.
Dear Scotty, out of your experience, is it a must to replace such sensors in pairs, for left and right readings and trims to be fully identical? Thank you.
P.S. Picture of a typical ML 55 AMG: https://1drv.ms/u/s!Alv3RQPn1ylAqE8bjbgqS9nj_mgh
It's not a mustache. You have to replace both of them but realize this they have to be exactly the same OEM parts because otherwise they wouldn't give the same exact readings and it would screw things up. Theoretically the stupid things are supposed to last forever because they don't eat up any of their internal components when operating correctly
Thanks a lot! Will attempt to get hold of OEM sensors. I suspect that some oil burning this motor is prone to might be the reason for the O2 sensor issues. Could be that the sensing elements of such sensors dislike oil 😉