Why do my 02 sensor code pops back up after I replaced sensor?? on 1998 Ford Explorer

Trying to pass my inspection.. 02 sensor needs replacing so I replace it! took it to auto zone to recheck and clear code! so they clear it,one hour later engine light came back on with the same code says replace 02 sensor!! that I already replace twice! what is going on?????? why won't it pass I'm so over it please help me!!

by in Austin, TX on September 14, 2013
1 answer 2 comments
ANSWER by on September 14, 2013
Common mistake everyone makes is to assume just because a code comes up that it means that sensor is bad! The 02 sensor is telling the computer there is a problem with the air to fuel ratio of the engine, not that it is defective! Can't tell without testing. What were the exact code number(s)? ALL codes!
COMMENT by on September 14, 2013
Ph153
COMMENT by on September 14, 2013
That's PO153. Which O2 sensor was replaced? Drivers side, passenger side, front or back? Dont know?