Opel Corsa D 1.2 63kW misfire quick fix

Vehicle is a 2011 Opel Corsa 1.2 (63 kW) that is experiencing occasional stuttering and reduced power, particularly when engine is up to running temperature. Initial test drive shows nothing, engine is running smooth when cold and idles nicely.

The vehicle then comes back later with the engine MIL light flashing under load. This time a scan indicates misfiring on cylinder 4.

The pic is from the Carista app.

No other codes are present. Swapping spark plugs leads to suspect a failed coil pack. In this vehicle, the coils are all connected in a single unit. Below is a picture of the original part.

A replacement aftermarket unit from Autodoc costs approximately 80 euros, and new spark plugs some 30 euros. Cleared codes, took it to a test drive; problem solved.