I wanted to take off the preheating plate to have a view of the exhaust manifold and how it connects to the rest of the exhaust system. But I had an accident. One of the bolts closer to where the cat is connected to the manifold was in a tight space and my wrench essentially was bending it while unscrewing and it tore off, leaving the rest of it inside...Now I know this won't cause any major issues, but now it bothers me that I did that.

I can't fix it myself, but I have to ask...will a potential mechanic have to lift off the whole engine to basically...bore through the hole to remove it + possible rethreading?

 

This kind of thing happens all the time, and there shouldn't be any reason to have to pull the engine out. You will probably have to remove the exhaust system south of the manifold to drill out the broken bolt.

 

Welcome to the club...the club of those who have broken awkward to access broken bolts, that is. Sometimes mechanics can weld something to the broken bit to help get some leverage and turn it out, other times they will drill. They'll have a solution for you, don't sweat it.

I did something similar last night: I overtightened one of the two long subframe bolts (the ones that are accessed through the hole in the control arm (the bolt is above)). Stumped on what to do next. I share your pain.