When to replace O2 sensor ?

[roadkill]

Just smogged my truck, and my CO was JUST under the max limit of 0.68 (calif.). The smog tech said it might be the O2 sensor, which he recommended changing every tuneup.

I have 120k, and running strong, and I know the sensor has never been changed. Any thoughts?
Thanks!

 

[Gofast]

I have not found any source that says an O2 will last more than 45K miles. I changed mine in the Trans Am at 64K and the truck at 165K miles.

You probable need to change them now. However, If the Cat converter is bad it will ruin the O2's. So make sure it's fine.

You'll know if the Cats bad due to a noticable drop in power or a rattling sound coming from it.

Good Luck

 

[Robert]

Originally posted by roadkill
Just smogged my truck, and my CO was JUST under the max limit of 0.68 (calif.). The smog tech said it might be the O2 sensor, which he recommended changing every tuneup.

I have 120k, and running strong, and I know the sensor has never been changed. Any thoughts?
Thanks!

At about $60 apiece for my 4 O2 sensors that would make for one expensive tuneup! On your '92 though you only have 1 or 2. I would say replace them when they go bad. There are probably lots of things that can cause a high CO reading so you might end up wasting $60-$120 because of a smog techs bad advise. Start with the easiest and cheapest things first like making sure your throttle body is clean. If it is running right (no smoke, normal power, no hesitation) and you passed then it isn't something I would worry about right now. Just remember that the next time for your smog check you might be over the limit. But then again, you might be under. I bought an '86 Ranger in '89 with 26K miles on it. Shortly after buying it I had to get the emissions checked. I was way over on something (I don't remember which one). I took it to Ford to have them repair it. They charged about $150 to clean my throttle body. I retested and passed with flying colors.