thomis

You guys recently helped me do a full tune up on my 98 s-10 4x4. Now I am having another issue. My CEL came back on and it's throwing another code (the first inspection fail was due to the light coming on and it threw spark plug #5 code, so I replaced all the plugs when I did the tune up).
By the way, the tune up was a success, it has run just fine for almost a month with no issues. But the light is back on. I wasn't able to get the re-inspect because I have been waiting on a replacement driver side mirror glass. Yes, the other reason they failed me was the mirror had a 2" crack.
Now the code it's throwing is the 3rd O2 sensor. I disconnected the negative cable for a while and re-connected it to see if the light came back on, and it did. My questions are:
The sensor is $53 and I don't have it so can I use seafoam, just as a temp fix?
Can I trust the code and just replace the sensor? I mean, do these sensors really go bad??
I was told there are 4 O2 sensors on this thing. How often do these need replacing?

oldchevy

Yes they do go bad. They will usually last about 100,000 miles. Some last longer, some do not. Every time I saw a code for the 02 sensor, the code went away when the sensor was changed. Make sure sure you replace the sensor with correct one. A downstream sensor needs a new downstream sensor. An upstream sensor requires another upstream sensor.