How often should you replace your engine's oxygen sensors?

While O2 sensors have no fixed replacement schedule, your driving style and the health of other engine components can ...
Ars Technica

Dumb Car Questions (need to replace O2 sensor)

Replace both the upstream ones at the same time so the reading will be consistent. You can keep the downstream one on there. The only difference between the two is the length of the wire. You can also ...