I have a 2002 Impala LS that I'm trying to get inspected in NY. It's throwing 2 codes, a P0135 and a P0327. I'm going to replace the oxygen sensor for the P0135, but I don't know how to diagnose and repair a P0327. This car is very high mileage and has a pretty major exhaust leak and the manifolds leak alittle when they're cold. I'm wondering if this could cause enough false knock to confuse the PCM into throwing a P0327?