I own a Toyota 4-Runner. Needed a new oxygen sensor to pass inspection. Toyota wants big bucks for a new one.
My mechanic called a help line (can't remember which one; costs $3/minute). Their Toyota expert suggested he clean the oxygen sensor element with carburator cleaning fluid (maybe it's acetone? don't know).
He did, and... it worked! No check engine light for three months (knock wood).
(steely)
common solution for 02 sensors. if you think about it, the sensor is actually IN your exhaust. has the potential to get extremely dirty..