Oxygen Sensor

How often do any of you replace the oxygen sensor? Was it done because of a problem or routine maintenance? What overall improvements did you notice if any?

mine was like 6 bux.. so i did it about once a year

When oxygen sensor harnesss first became common place, manufacturers stated that it was a maintenance item and should be changed every X years or XXX,000 miles/km.

Not many people bothered doing this and guess what...those O2 sensors kept working fine way beyond their supposed expiration dates.

Since the sensors are hooked up to the OBD II system, I would just keep driving on those 02 sensors until the computer detects a fault and gives you code.