Search Button

Search

Account Button

Account

Basket Button

Basket Basket

Search Suggestions

Categories

Products

View All Results

Car
Bike

Find Oils & Parts

Select Your Motorcycle:

Manually Enter
Modified Vehicles

A Guide to Ignition Coils and Common Problems

The ignition coil is a fundamental component in a vehicle's ignition system, playing a crucial role in the process of starting and running an engine. We will discuss ignition coils, including what they are, their main functions, common problems, symptoms of issues, testing methods, and the cost and time to replace them.

Understanding the common problems, symptoms, and testing methods associated with ignition coils is essential for maintaining optimal engine performance. Promptly addressing any issues with the ignition coil replacement is crucial, as it helps to prevent further damage to the engine and its associated costs.

Whether you choose to take a do-it-yourself approach or seek the help of a professional, prioritising the health of your ignition system is crucial in guaranteeing a seamless and dependable driving experience.

What is an ignition coil?

An ignition coil is an essential part of a vehicle's ignition system. It's a type of transformer that amplifies the electrical voltage supplied to it, transforming low-voltage electrical power from the battery into the high-voltage energy (thousands of volts!) essential for igniting the spark plugs. These sparks ignite the air-fuel mixture inside the combustion chamber.

Where is the ignition coil found?

The ignition coil sits between the battery and (in the case of older vehicles) the distributor that sends out the voltage it produces to each spark plug. In more modern vehicles with an electronic ignition system that uses a computer rather than a distributor, the coil is likely to be mounted directly to the spark plug, or a pair of spark plugs. And so, modern engines can have multiple coils.

Function of an ignition coil

The main purpose of an ignition coil is to produce a powerful spark that initiates the combustion of the air-fuel mixture in the engine's combustion chamber. This controlled explosion is what propels the engine's pistons and ultimately powers the vehicle. The ignition coil is essential for initiating the combustion process, making it a crucial component of the engine's overall performance.

Common ignition coil problems and their symptoms

  1. Faulty Coil Windings:

When the windings within the ignition coil become damaged or compromised, it can lead to erratic engine performance. Symptoms may include misfires, poor fuel efficiency, and a noticeable decrease in overall engine power.

  1. Cracked Insulation:

Over time, the insulation around the coil windings can crack, allowing electrical currents to leak or cross over. This can result in a weak or inconsistent spark, causing engine misfires, rough idling, and even difficulty starting the vehicle.

  1. Internal Short Circuits:

Internal short circuits can occur due to manufacturing defects or prolonged wear and tear. This occurrence has the potential to interrupt the smooth flow of electricity in the coil, resulting in engine misfires, stalling, and heightened exhaust emissions.

  1. Corrosion and Rust:

Ignition coils are exposed to various elements under the hood, making them susceptible to corrosion and rust. Corroded connections can hinder the coil's performance, leading to poor ignition and potential engine failure.

  1. Faulty Spark Plug Wires:

If the spark plug wires are damaged or faulty, it can impair the ignition coils' capacity to transmit a robust spark. Symptoms include rough idling, engine misfires, and a noticeable drop in fuel efficiency.

How to test an ignition coil

If you're having ignition issues, here are some methods to test an ignition coil:

  1. Resistance Testing:

Use a multimeter to measure the resistance across the primary and secondary windings of the ignition coil. Deviations from the specified resistance values in the vehicle's manual may indicate a faulty coil.

  1. Spark Tester:

Use a spark tester to check the strength and consistency of the spark produced by the ignition coil. Inconsistent or weak sparks suggest potential issues with the coil.

  1. Visual Inspection:

Examine the ignition coil for physical damage, such as cracks, corrosion, or signs of overheating. Any visible issues may indicate a need for replacement.

Why does an ignition coil fail?

A hot engine bay is a challenging place for any sensitive equipment, including a coil. And, given that the ignition coil is situated directly above the engine, this doesn't help either. The coil gets alternately cold and hot, and also experiences strong vibrations from the engine, both of which will break up the coil's windings and insulation over time.

Additionally, a large cause of coil failure is voltage overload caused by worn spark plugs.

How much does it cost to replace an ignition coil?

The cost of replacing an ignition coil can vary depending on the make and model of the vehicle, as well as the type of ignition coil used. The typical cost for a single ignition coil can range from £20 to £150 or more. Some vehicles may have multiple ignition coils so that the overall replacement cost can increase accordingly.

It's important to note that labour costs for professional installation can also contribute significantly to the total expense. Mechanics typically charge an hourly rate for their services, and the time required for ignition coil replacement can vary depending on the vehicle's design and the accessibility of the ignition coils.

How long does it take to change an ignition coil?

The time required to change an ignition coil depends on several factors, including the vehicle's make and model, the number of ignition coils needing replacement, and the accessibility of the coils. On average, replacing a single ignition coil can take approximately 30 minutes to an hour.

However, if multiple coils need replacement or if the coils are located in challenging areas that require additional disassembly, the process may take longer. It's advisable to consult the vehicle's manual or seek professional advice to get a more accurate estimate of the time needed for ignition coil replacement.

DIY vs. Professional replacement of an ignition coil

While some automotive enthusiasts may choose to replace ignition coils themselves, it's essential to weigh the pros and cons of a DIY approach. DIY enthusiasts should have a good understanding of their vehicle's ignition system, be comfortable working with electrical components, and possess the necessary tools.

For those without the required expertise, we recommend that you seek professional help. Professional mechanics have the experience and knowledge to diagnose ignition coil problems accurately, ensuring a precise replacement that adheres to manufacturer specifications.

Preventative maintenance tips to prolong the lifespan of your ignition coil

Extend the life of your ignition coils by incorporating easy maintenance practices into your routine. Regularly check for signs of wear, ensure electrical connections are secure, and promptly address any identified issues. These simple steps function as a shield against unexpected breakdowns, fostering a healthier engine overall.

Choosing the right ignition coil

Elevate your engine's performance by selecting the perfect ignition coil. Consider your vehicle's model, compatibility, and durability. You can use our part finder tool to find the right products for your car or motorcycle and identify the type of ignition coil you need; enter your car details and navigate to Parts & Everything Else > Spark & Glow Ignition.

Impact of ignition coils on engine performance:

A properly functioning ignition coil guarantees a powerful spark, enabling the fuel mixture to burn completely, resulting in optimised power and increased engine responsiveness. On the other hand, a defective ignition coil can result in misfires, unstable idling, and diminished power, while also causing higher fuel consumption and more detrimental emissions.

Contemporary engines with electronic control systems depend significantly on the accurate timing and strength of the spark produced by the ignition coils to ensure optimal engine performance and adhere to strict environmental regulations. Therefore, maintaining the health of ignition coils is integral to preserving engine integrity, ensuring longevity, and sustaining overall vehicle performance.

Comparing OEM and Aftermarket Ignition Coils:

OEM coils, tailored for specific vehicle models, guarantee a perfect fit, consistent performance, and long-term reliability, adhering to high manufacturer standards. They typically include warranties and seamless integration with a vehicle's electronic systems.

Aftermarket coils offer a more extensive selection at potentially lower costs, with some matching or surpassing OEM quality. Quality can vary significantly among aftermarket products, and choosing a reputable brand is crucial for ensuring compatibility and durability.

All the aftermarket brands we supply offer quality to OEM standards, backed up by a warranty so you can buy with confidence.

Questions?

If you have questions, get in touch with our technical experts via phone, email or chat.