whats the easiest way to tell if an O2 sensor is bad?

[metasonic]

whats the easiest way to tell if an O2 sensor is bad? My air fuel gauge never goes past lean, my exhaust pipe is black like i'm running rich, i'm going through gas like crazy, and i'm hitting fuel cut if i have less than 3/4 of a tank. I think it may be the o2 sensor since it seems like i'm running rich, but the car thinks is lean... any ideas?

 

[crazyjoe]

If your primary O2 is bad, you chould be gettnig a CEL with code # 125.

You live right near wehre I work(Troy), and I have a pocketlogger we can check your O2 voltage with...PM me and we'll set up a time to meet up and check some of that stuff out.

 

[jb talons]

By everything you listed, it sounds like all the signs of a bad O2 sensor. But to be sure get crazyjoe to check it.