I had to get a universal o2 sensor by bosch since they didn't have the sensor for the 3s. What 02 sensor do you guys have? I'm getting a code 21 in diagnostic mode but I don't get a CEL, unless I am in diagnostic mode. Does this mean my o2 sensor is going out or is it the wiring?

are you checking the codes with the car running?
you should be checking them with the car off, with the igniton in the ON position.

I know I did it with the car running but I think I have done it with the car off too.

I get the code with the engine off.

how do you install an o2 sensor regarding the wiring?

i got that code too and replaced my o2 sensor and it went away