My 2010 Traverse was just diagnosed with a "bad" catalytic converter. In addition, I was told that the O2 sensors were also "bad" and need to be replaced. When asked what "bad" meant, I was told that they weren't working. My question is, is there a relationship between the cat converter and the O2 sensor in that one killed the other part? I was also told that the O2 heat shields were missing....could this have played a part in these parts going "bad" and how do heat shields go "missing"?

 

what codes were setting?

The front 02 reading are primarily used for fuel trim calculations but the secondary function is to check convertor operation. It does this by comparing switch rates of the front and rear 02 sensors. if the cats are working the rear 02 switch slower...if the cats are not performing redox reactions to the exhaust gases, the switch rates are similar.
can a bad 02 sensor kill a cat, yes, it usually happens when the customer continue to drive with a un-repaired fault.

the heat shields are bolted to the floor pan using flanged nuts. the shields rust where they contact the nuts and fall down and rattle....so they are removed. order new ones and have them bolted in place.

 

The O2 sensors may be defective . Any other codes set ?

Were it me , I would search youtube for O2 diagnostic videos . Then try to connect a scan tool that will display real time data . Determine if the O2 sensors are really bad .

Repair as necessary . The O2 sensors are not too expensive .

Replacing the cat would be my last resort . I think they can be pricey .

How many miles on the vehicle ?

But , first , I would do a visual inspection , looking for obvious wiring problema .

God bless
Wyr