[GJSmackdown]

I have a 95 Explorer XLT with 152,000 miles on it. Gave it up a tune up at around 98,000, changed plugs, wires, pcv valve, and fuel filter. The guy at the garage I had it done at said don't worry about the O2 sensors until they go bad but I don't like to wait until stuff goes bad to have it fixed. If I can fix something before it goes bad I prefer to do that. So my question is, is it recommended to change my O2 sensors even though I have had no problems with them? I don't know if they were ever changed previous to me buying it.(had 86,000 miles when i bought it)

 

[ax0n]

I'd wait. I have an Aerostar with 160K miles on it and it's on the first one, my Escort's went out around 120K, my Focus's went out at about 70K.

When either one goes, the Check Engine Light usually comes on. The code will tell you which it is. Depending which one goes out, when it finally croaks your truck will either run like crap and get worse gas mileage than usual (pre-cat HO2S), or the check engine light will just glow and nothing else will apparently be wrong.

The upstream (Pre-cat) O2 Sensor is used for tuning the Air/Fuel mixture. The downstream (Post-cat) is just used to test the catalytic converter. With the exception of the Altima my dad used to drive, no car I've ever worked on or owned has had the post-cat O2 Sensor go out.

Basically, if you want to replace it, go ahead, but make sure you get a genuine motorcraft sensor. I know they're more expensive, but I've had nothing but problems with the botch errr I mean Bosch sensors from places like Advance Auro Parts or AutoZone.