If my Catalytic converter is failing, what symptoms would I expect to see please??

Thanks in advance.

 

anyone?

 

Only experience I have had on a cat was when it was rattling inside. Sounded like a loose muffler clamp. I hear they can starve the engine of power, give poorer MPG and set codes when they plug up.

 

thanks

 

if it's really bad, then it will start faling apart on the inside and then you will hear a rattling noise like mr... said.
but first you will have a bad exhaust test. too much HC in the exhaust fumes, but that can also mean problems on some other part of the engine.

anyway, the test can be made.
on idling, Cat should be only warm. couple of quick snaps on accelerator should rise the Cat tremperature significantly. also the exhaust fumes temperature should rise and tester should show more HC, but not too much.
if Cat temp. stays low and exhaust shows high levels of HC, Cat is dead and needs replacement.