Ignition coil
Produces the high voltage needed by a spark plug.
Often directly above each petrol engine’s spark plug.
Magnetic energy stored in the primary circuit produces a high-voltage pulse when switched.
An electrical step-up station for a tiny lightning bolt.
A weak coil may misfire under load, but its plug, connector and supply also need checks.
Plugs and filters use engine-specific service guidance. Pumps and injectors are normally assessed through pressure, leakage and electrical tests.
Spark-plug service is usually less involved than direct-injector or high-pressure-pump replacement; coding and access can add work.
BMW coil-on-plug packaging places the coil near its plug rather than using one shared distributor.
BMW spark-ignition petrol engines, including petrol plug-in hybrids. Diesel engines do not use spark-ignition coils.