How can you test an o2 sensor to see if it's gone/going bad?

 

Generally you will throw a code if it's out. As far as testing it, They can be tested both in the car and out. If you have a high impedance volt meter, the procedure is fairly simple.

http://www.gnttype.org/techarea/ecms...O2sensors.html

Read through that.

 

Hook up a scan tool, not a code reader, and see if it's reading.

 

FYI I get like 33mpg average.


hmm would the scanner they use at autozone be able to check that?

 

What are the signs of a bad o2?

I get backfires shifting to second...
WOT had a good size backfire when shifting to second and another from second to third...
Car seems to be running very rich.
Often causing a bogging down feeling.


downstream o2 would not effect drive-ability if it went bad correct?

Upstream o2 could go bad and cause drive-ability issues without throwing a cell correct?