Ignition coils: Practical tips for service

Unfavourable operating conditions can lead to increased wear of the ignition coils, reduce the service life of the ignition coils or cause damage to the ignition coils

Like many other components of a vehicle, the ignition coil is subject to a certain amount of wear. Its service life is normally between 60,000 and 80,000 kilometres - however, a variety of factors can lead to a reduced service life. Before replacing an ignition coil, these factors should be checked.

Internal short circuits lead to overheating

With increasing age of the ignition coil, the risk of overheating as a result of internal short circuits increases. Worn spark plugs may also contribute to this effect. They require a higher ignition voltage, thus putting more stress upon the ignition coil.

Faulty voltage supply

If the ignition cables are damaged or the battery power decreases, this will lead to an insufficient voltage supply and longer charge times for the ignition coil. In the process, switching devices or end stages in the control unit can be damaged - which can ultimately lead to an ignition coil defect.

Mechanical damage

Ignition coils can also be damaged by marten bites. Other mechanical damage includes insulation damage arising from the escape of oil - such as when a valve seal no longer closes sufficiently.

Contact error

If the ignition coil housing is damaged and moisture penetrates into the area of the primary and secondary coil, this can cause spark-over resistance. The cause of this error may be faulty designs of spray water nozzles, with heavy rain or when an engine is washed. Road salt during the winter can also be the cause.

Thermal problems

Pencil coils, in particular, are subjected to extreme heat. This can also shorten the service life of an ignition coil.


Vibrations in the engine bay can lead to a coil brake with pencil coils, in particular.