What does an Ignition Coil do?

The ignition coil is a component of the ignition system. It is essentially an induction coil, an electrical transformer, that produces a very high voltage current from the battery's 12V low voltage current. Generally it produces around 50,000 volts.

The high voltage current is necessary for the spark plugs to create a spark and ignite the fuel in the engine's cylinders.
Most new cars have one small ignition coil for each spark plug (mainly because newer cars do not have a distributor, ignition is regulated electronically). Older cars will have one (or even two) ignition coils for all spark plugs.

How do you know there is something wrong with an Ignition Coil?

• When the electrical connectors have corroded.
• When the car's fuel consumption is higher than usual.
• When the engine misfires and does not run smoothly.
• When the 'Check Engine' light is on.
• When the car idles rough (unsmooth idling of the engine).
• When the car fails an emissions test on an elevated level of hydrocarbons.
• When the car does not start.

When should you consider a Ignition Coil replacement?

Over time, an ignition coil can wear out due to general use. Additionally the coil can malfunction due to bad ignition leads that prevent an adequate current to flow through the leads; the extra resistance that occurs then can damage the coil. It is therefore important to have the ignition leads measured for resistance too when the coil is faulty, to prevent the a similar problem with a new ignition coil. Professional and timely maintenance is essential to prevent further damage.

Should you experience problems with an ignition coil then it is advisable to have it inspected and, if necessary, have it replaced. Remember, always service the ignition coil as and when stipulated in the guidelines set out by your car's manufacturer.

What happens during an Ignition Coil replacement?

• Mechanic will read the ECU for possible fault codes related to the ignition system.
• Mechanic will inspect the ignition system and ignition coil, in the case of Coil-On-Plug coils each individual lead and coil will be tested.
• If necessary, the mechanic will replace the damaged ignition coil(s).
• Mechanic will advise if any other parts need to be replaced (like the ignition leads).
• Mechanic will inspect the ignition system again and, if necessary, test drive the car.

How much does an Ignition Coil Replacement cost?

The cost of replacing the ignition coils depend on your car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having an ignition coils replaced by ClickMechanic, by selecting your car at the top of this page!