obd2 has two oxygen sensors? i have three for some reason, i dont know if my car has been messed with or not but i do know that my car is a theft recovery with a *clean* title. it was found with everything stock except it had no wheels. and the cast iron exh manifold has one o2 sensor and the stock cat has two. h: ill take a peek down under soon to see where the o2 wires lead to, thanks lots for all of the replies.