I just had an O2 sensor installed before the catalyst. I am not sure this sensor is for the rear or the front, because some websites say it is for rear use but others say it is for the front.

Will it be a problem if i actually put a rear sensor before the catalyst?

Thanks in advance.

 

Yes it will be a problem, the rear o2 sensor just monitors the efficiency of the catalytic converter. The up stream o2 sensor monitors the a/f ratio.


-Eric