Hi guys,im wondering on the AYP engine there is two o2 sensors.The first is for the fuel mixture,but i don't know the second is it only for monitoring the work of the cat or it also is used for the fuel mixture.I am asking because i removed my cat and replaced it with a pipe.And when there is no cat the second o2 sensor is getting equal values with the first lambda sensor and the check engine light is on.Since there is error from it,will it affect mu fuel efficiency and the work of the engine,or it only displays that there is a problem with the cat.Thanks