1997 Subaru Impreza Outback Sport - How much do I need this?

My check engine light came on, and after a diagnostic, the rear oxygen sensor needs replacement. How crucial is it to replace the rear oxygen sensor for a 1997 Subaru Impreza Outback Sport?

That sensor monitors your catalytic convertor’s effectiveness. If you don’t replace it, the check engine light will never go off and if something more serious occurs, you won’t know it because the CEL is has been on for a long time.

Plus, if you have emissions testing where you live, the car will fail.

A cheap version of the part is $21 on RockAuto, just replace it.


Thanks Mustangman. I appreciate it. That was very helpful.

I have one more question. The Subaru notice states that the rear oxygen sensor needs replacing. Does “rear” oxygen sensor mean the “downstream” one on a 1997 Subaru Impreza Outback Sport? Or does it matter, especially since in RockAuto the sensors for sale say they are both upstream and downstream? Thanks.