General How do you know if your O2 sensor is dead?

[94Jettameowpsst]

Just wondering, obviously i have a logger but how do you know if your o2 sensor is dead? My trims for some reason stay 118 low, 86 mid, 81 high. Doesn't matter what setting i have my MAFT set at. Any feedback would be helpful.

 

[steve]

It reads 0 or doesn't switch in closed loop. Dieing ones start switching slow and cause bad gas milage.

Steve

 

[94Jettameowpsst]

Sorry, but what do you mean switching slow?