I would just take it off and see what happens....But do not throw it away. I've used exhaust wrap around my cat before but I'm not sure if it traps water and accelerates rust.Howdy!
About 4-5 years ago I repaired the heat shield above the muffler. 3 of the four mounting locations had rusted out. I was unable to loosen the factory nuts (and at least one of the posts itself started to turn when i tried. So I added a big washer and new nut on top of the old ones and it was fine. Well Sunday, the heat shield fell off. The one remaining factory mount and all 3 of my new ones had rusted. It fell off while driving so the heat shield itself got bent up, but I may be able to fix that.
Now I have a dilemma. Three of the holes on the exhaust shield are now about 1.5”+ in diameter, the nuts I added are now rusted on and there aren’t enough threads on those posts to add another but to the stack. If I take it to a dealer, the fact that one of the posts started to turn a few years ago worries me. I bet replacing the posts is a very expensive affair. I called a local (trusted) muffler shop and the guy on the phone told me to just drive it without it. I looked at where the shield is located and don’t see any wires or cables in that area. Just sheet metal for the floor under the third row seats. But I can’t imagine Toyota would spend the money to put a heat shield on there if it wasn’t needed.
So, what do you guys think is the best solution to this? Is it safe to drive without this shield?
Catalytic converters need to operate at a certain temp to stay clean. So while many people take them off and never have issues, it might accelerate the clogging of your cat. Also Toyotas seem to have oversensitive emission system that like to throw P0420 codes, which I suspect is because people are taking these heat shields off and the cat is not operating hot enough.
You can try patching it up with some sheet metal and rivets? Or learn some welding. Or call the exhaust guy back and tell him you'll pay him good money to do it.