Hey guys aight check it, I keep getting a check engine light and when we put it on the computer, it says that o2 sensor in location 1 is not operating correctly. Now I never had this problem until i installed my free flow cat and when they welded on my o2 sensor again, they actually put it right before the o2 sensor. There is also an o2 sensor right at the tip of the exhaust manifold(b16a2). Is this something i should try to work with or is this a problem that cannot be resolved? Thanks