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Starting at $156.95, AutoBuffy stocks 1 direct ignition coils from Standard Ignition for the Bmw Z4. A direct ignition coil (also called a coil-on-plug) sits directly over each spark plug and fires it independently. When one fails, that cylinder misfires continuously, triggering a check engine light, rough idle, and real damage to the catalytic converter if ignored.
The main decision is whether to replace one failed coil or the full set, and whether to choose OEM-equivalent or upgraded output. Coils on the same engine age at the same rate, so replacing all of them at once when one fails is common practice and saves labor. Match the coil design — pencil-type, square-body, or remote-mount — to your engine's specific configuration.
| Option | Best for | What you get |
|---|---|---|
| Single OEM-equivalent coil | One confirmed failed coil on a lower-mileage engine | Drop-in fit, matches factory output, lowest upfront cost |
| Full set — OEM-equivalent | High-mileage engines where remaining coils are likely near end of life | Uniform coil health across all cylinders, one labor charge covers all |
| Performance / high-output coil | Modified engines, forced induction, or upgraded spark plugs with wider gaps | Higher spark energy improves combustion efficiency under demanding conditions |
| OEM dealer coil | Vehicles still under powertrain warranty or with repeated aftermarket coil failures | Exact factory specification, longest documented service history for that platform |
Disconnect the battery, unplug the coil's electrical connector, remove the single retaining bolt, and pull the coil straight up off the spark plug. Seat the new coil firmly, snug the bolt to the manufacturer's specified range — consult your service manual since specs vary by platform — and apply a small amount of dielectric grease to the plug boot interior before reinstalling. Clear any stored misfire codes after the repair and confirm with a short test drive.