An ignition coil is a high voltage and low current transformer that converts the 12 volts power supply from a car’s battery to the spark plug.

This helps to start the engine and instigates combustion. There have been many changes to the type and design of ignition coils over time. However, their basic working principle remains the same.

They rely on Faraday’s Law of Electromagnetism for generating this high voltage.

When a voltage passes through the primary windings, a magnetic field is created. When the voltage is stopped or interrupted, the magnetic field collapses. This generates a voltage in the secondary windings.

The secondary windings then feed this voltage to the distributor through a well-insulated high-voltage wire. If the ignition coil is not working properly, you will find it difficult to fire your engine.

It can also lead to your car losing power and stalling when you drive.

Types of Ignition Coils

The different types of ignition coils and their working mechanisms are discussed below:


In the conventional ignition coil, the battery powers the primary circuit through a resistor.

Current flows through the windings of the primary coil, thereby creating a magnetic field.

Once the points open, the electric circuit is interrupted, which breaks the magnetic field.

In an instant, the current flows into the spark plugs through the distributor caps.

These early ignition coils though simple, had their shortcomings as they were prone to breakdowns and were not very efficient.


The electronic ignition coil is similar to a conventional variant.

The major difference is that here a pickup coil is used to control the module instead of the distributor cam and panels in a conventional ignition coil.

Electronic ignition coils are more efficient and reliable than conventional ignition coils.

Distributor-Less (DIS) Ignition Coil

A DIS ignition coil is designed to provide more energy from multiple coils.

There is a magnetic triggering device to determine engine speed and crank position. It consists of a crankshaft position sensor (CKP) and a camshaft position sensor (CMP).

These sensors provide the information for determining spark timing.

Coil-on-Plug (COP)

The COP ignition system has all the electronic controls found in a DIS ignition system.

However, instead of two cylinders sharing a single-coil, each COP coil only shares one cylinder.

This means that COP coils can generate a high voltage of up to 50,000 volts.

They produce much stronger sparks and are hotter too.


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