The chances of all 3 coil packs going bad at the same time are tiny so you'll probably only need one if anything. If one of the coil packs is bad, you will get P0300-P0306 codes which means the engine is missing and will narrow it down to specific cylinders. Since each coil pack controls 2 cylinders, you will see 2 miss codes almost always. If your engine isn't missing, then your coils are fine so don't worry about them. If you do get a code (or codes), you can switch coil packs - if the miss code moves with the coil pack, you got a bad one. If the miss stays with the same cylinder(s) you have another issue (like plugs, wires, coil pack boots, injectors, valvles, etc..).