My check engine light kicked on after I just passed 50,200 mile on my 2006 MAZDA 3 Hatch... it came out as a p0161 oxygen sensor error. The replacement sensor is about 400+ dollars at checker and auto zone... what should I try to do before I pay out that cash?

 

if its bad its bad, but u need to make sure its the 1st (upstream $350+) or the 2nd one (downstream $75+), then you need to find out why it went bad, just replacing the bad part (if its really is bad) and not finding out why it went bad is just setting u up to buy another one in a couple thousand miles, good luck