After fitting an MSD 8241 coil pack (e.g. Fiat Punto 1.2 8V) the car won't start or shows P0351/P0352 misfire codes. What should I check?

The 8241 is a wasted-spark pack with two coils. If the engine doesn't start, try swapping the leads going to cylinders 1-4 with those going to 2-3; the firing pairs are probably reversed. P0351/P0352 (ignition coil A/B circuit) codes are rarely caused by the coil itself: check that the pack's shape and terminals match the original and that the spark plug wires and their ends are in good condition. Send us photos of the wire ends and connections if the problem remains.