Hi everyone. I have searched for threads on o2 sensor replacement on 2011 x5 35d. My question is BMW service manual says replace the o2 sensor at 100,000 miles. I am not throwing any codes, car is running normal and I just want to throw the dumb question out there "should I replace this" as normal maintenance? The car went out of extended warranty at 100,000 miles and I am doing all maintenance but am addmittedly ignorant around sensor "stuff" .... thanks for all helpful answers - this is a great forum!