92 XJ w/ 162K, when to change the 02 sensor?

Mine runs great, shows approx 15-16 mpg since I put 30x9.5's on it - was just curious when to change the 02 sensor? And oh yeah since 120K EXACTLY my "Check Maint" light(the one on a timer to be reset by dealer) has been on. Thanks, Heinz

Unless you have the right tools, those o2 sensors can be a challenge. They don't always want to come out without a fight. You may be better off going to your local Pep Boys and have them do it for 80-90 bucks.

O2 sensor being a challenge? I must have gotten lucky.