I went to advanced auto and they the checked out why my check engine soon light was on. I drive a 97 5spd, and it said front 02 sensor and knock sensor. so do i replace o2 sensor on the front exhaust manifold or rear manifold? Also could it through a knock sensor malfuction code because the sensor is shot or because something is triggering the engine knock.

 

Replace the O2 sensor first. (From the info provided, I can't really tell which one of the fronts you need. The exact code number would have helped.)

Then reset the ECU and see if the Knock Sensor code comes back.

Usually fixing the O2 sensor will fix the KS code as well.

 

Just remember a KS code alone will not turn on your check engine light. You may have had it for a while and the o2 is what finally caused the light to go on. Bank 1 sensor 1 is the first o2 on the manifold closest to the front of the car, i just changed this one a few days ago.

 

but i swear the knock has to be hit too cuz i lost to a 1.8t with cai only and i have down pipe n headers isnt knock sensor suppose to be like 20hp?