My o2's were 5 months old when they went bad. Since they were new I checked everything else but them. Then after 2 weeks of bs the check engine light finally popped on and it was an o2 code. We thought is was everything from a vacuum leak, to bad springs, to cracked plugs. The car was surging like crazy, stalling, and felt very choppy. If thats what yours is doing you may want to borrow someones o2's just too rule it out.