Not absolutely sure what caused the lock-up.

Anyhow, I fixed the steering. Shined a flashlight down the side of the engine, and there's a plug dangling. Quick snap into the other end and all is well.

EGR's still screwed up. I'll poke around and see if I can fix that. If not, I'll take it back and get the mechanic to do it. At least it's nothing too crucial.

Thanks for the help.