The recent thread about o2 sensors reminded me that last time I tried to change my upstream o2 sensor I couldn't get the old one out so I returned the new one. There is nothing wrong with my car but I am a believer of changing them at 100k miles if it's easy and cheap enough. On my car it's fairly accessible, though it's covered by the heat shield a bit so I can't get direct access. I tried various o2 sensor sockets and it just wouldn't turn. I tried spraying some penetrating oil and that didn't help either. I gave up because I didn't want to cause more problems than I was trying to solve. 2010 escape 2.5...