My converter started rattling at low rpms and I thought it would be the heat shield. Checked the shield, all 4 bolts tight. Sound is defiantly coming from the converter. Is it possible that the media inside could be cracked and vibrating?? 02 Accord coupe 2.3L auto

 

it sure is possible! No check engine light? If it's definately the cat and not the heat shield, then you need a new one.