Expert: Mike Evans - 2/28/2010

Question
I have a 97 chevy pikup 3/4 ton.  with a 350 vortec, with 4 heated o2 sensors.  1 cat converter is burnt out the other is not.  will this affect the performance in any way?  also can i remove the cat converters w/out the ecm turning my check engine light on?

Answer
    The purpose of the oxygen sensor located downstream of the converter is to tell if the converter is working properly.  If the upstream sensor is not working then the ECM cannot tell that the converter is bad.  However, if the upstream sensor is not working the ECM will operate in open-loop mode, running much richer and using much more gas.  So, there is no good reason not replace the converter; the extra gas used will more than make up for any savings in avoiding the repair.