the easiest way to check an o2 sensor without a scantool is by back probing the sensor signal wire while its connected to the engine with the engine running. you will need a multimeter to do this. the voltage should fluctuate. if it doesnt, then your sensor is bad. the computer should turn on your check engine light for any o2 sensor failure. most common faults are o2 sensor heater circuit failure or o2 sensor slow response.

 

Ok thanks for the input, i'll check out my O2 sensor today since i have a multimeter. Since i have to replace my boost gauge what is a good route to go. The one that broke was an autometer and a good tuner in town told me autometer aren't that great. I came across prosport any other gauges that i should consider (i'm not looking to spend a "defi" arm and a leg).