not alot of space for a wrench...should the engine be cold??

 

engine should be cold if it'll come out cold cuase otherwise you might get burnt. Most auotparts stores sell O2 sensot sockets that have a slit up the side for the wire this way you just put on a long extension on a ratchet and go at it if you need more levrage extend the socket out of the engine bay and put a pipe on the end of it