You can replace one coil at a time or all at the same time. I would however recommend having all spark plugs replaced with the coils so you do not have to remove coils twice.

Do I need to replace all ignition coils at once?

You do not have to change all the ignition coils at the same time.

Do ignition coils have to be in order?

Are ignition coils numbered? – Quora. , Freelance car, motorcycle, and electronics nerd. Not usually intrinsically numbered. As soon as you install them on the engine however it’s common to refer to them as “number 3 coil” or similar.