can this converter cause a need to replace the engine. That is what the dealership explained to us. The converter blew back into the engine causing sensor failure and the need to have the engine replaced.
catalytic converter on 2005 Nissan Armada
This does not sound like it makes any sense to me, unless the engine caught on fire. The CAT can't really 'blow back' it can be restricted and cause the engine to get hotter than normal, from over working. What is your Nissan doing that it is in the shop. Did it stop running?