Where Are Ignition Coils Found?

Ignition coils are found on engines that use spark plugs—primarily gasoline (petrol) spark‑ignition engines. In modern cars they sit directly on top of each spark plug (coil-on-plug) or in a coil pack mounted on or near the engine; in small engines like lawn mowers they’re built into a magneto near the flywheel under the shroud. Diesels generally don’t have ignition coils.

What ignition coils do and where they live

An ignition coil transforms a vehicle’s 12-volt supply (or the magneto’s low-voltage output) into the tens of thousands of volts needed to jump the spark-plug gap. The way a manufacturer packages the ignition system determines where you’ll find the coil: either on each plug, grouped in a pack, near a distributor (older designs), or integrated with a flywheel magneto on small engines.

Typical locations by engine type

Modern passenger cars and light trucks

Most late-model gasoline vehicles use coil-on-plug units positioned at each cylinder. Depending on engine layout and covers, they may be visible on the valve cover or tucked into spark-plug wells beneath a plastic engine shroud.

The following points outline the most common mounting arrangements you’ll see in cars and light trucks:

• Coil-on-plug (COP): Individual coils sit directly on each spark plug, typically atop the valve cover (inline engines) or along both valve covers (V6/V8). Some are recessed in deep plug wells under a plastic engine cover.
• Coil packs (multi-tower): A grouped pack feeds multiple cylinders via short, equal-length plug leads; usually mounted on the engine’s front, top, or side, near the intake manifold or timing cover.
• Single coil with distributor (older vehicles): A single canister-style coil mounted near the distributor on the engine or on the fender/firewall sends high voltage through the distributor cap and rotor to each plug wire.
• By layout: Inline engines cluster coils along one side or atop the head; V engines split coils between banks; boxer engines place COP units on the outer sides of the heads.

In all of these designs, the goal is to minimize high-voltage lead length, improve reliability, and ease service—hence the trend toward COP units directly at the plug.

Motorcycles, scooters, ATVs, and snowmobiles

On powersports machines, ignition coils are typically mounted close to the cylinder head to keep plug leads short. Many modern bikes use stick-type COP coils that drop into the head; others mount compact coils under the fuel tank or along the frame with a short plug wire.

Small engines: mowers, chainsaws, generators, and garden tools

Small two‑ and four‑stroke gasoline engines use a magneto ignition system. The ignition coil (often called an ignition module) is bolted next to the flywheel under the plastic shroud; the flywheel magnets induce current in the coil as it spins, generating spark for the single plug.

Marine and aviation

Gasoline marine engines use COP units or coil packs under the engine cowling (outboards) or atop/along the engine (inboards). Many piston aircraft engines use dual magnetos with internal coils mounted on the accessory case; these magnetos serve the same purpose—creating high voltage for the spark plugs—without relying on a car-style external coil. Turbine aircraft and pure electric propulsion do not use ignition coils.

Where you won’t find ignition coils

Diesel engines use compression ignition and typically have glow plugs rather than spark plugs, so they do not use ignition coils. Full battery-electric vehicles have no internal combustion engine and therefore no ignition coils. Hybrids and plug‑in hybrids with gasoline engines do use ignition coils as described above.

How to locate the ignition coils on your vehicle

If you’re trying to find the coils for inspection or replacement, the following steps will help you locate them without guesswork.

1. Remove any plastic engine cover to expose the top of the engine.
2. Follow the spark plug path: look for either pencil-like COP units bolted over each plug or a coil pack feeding short plug wires.
3. Check along the valve covers (V engines) or the top/side of the head (inline engines) for bolted coil modules with electrical connectors.
4. On older vehicles, find the distributor, then look nearby for a cylindrical single coil with a thick high-tension lead.
5. On small engines, take off the recoil starter housing/shroud; the ignition module sits next to the flywheel with a small air gap.

Once you’ve identified the configuration, note connector locks and bolt sizes; coils are usually held by small bolts and a single electrical connector per unit or per pack.

Common signs a coil is failing

Because coils live in hot, vibrating environments, they can crack or break down over time. Watch for these symptoms to pinpoint a bad coil.

• Misfires under load or at idle, rough running, or hesitation, often with a flashing Check Engine light.
• Diagnostic trouble codes such as P030X (cylinder misfire) or P035X (coil circuit fault) tied to a specific cylinder.
• Hard starting, poor fuel economy, sulfur smell from the exhaust, or backfiring.
• For small engines: starts cold but dies hot, or weak/no spark; visible cracks in the module or damaged plug boot.
• Visible arcing, oil intrusion in plug wells, or moisture causing secondary leakage around COP boots.

Prompt diagnosis prevents catalytic converter damage from prolonged misfires; replace suspect coils and address spark plugs or boot seals at the same time.

Safety and service notes

Ignition systems generate dangerous high voltage. Turn the engine off, disconnect the battery (12 V vehicles), and use insulated tools before handling coils or plug leads. Follow torque specs when reinstalling coils, apply dielectric grease to boots where specified, and replace aging spark plugs to reduce coil stress.

Summary

Ignition coils are found wherever a spark-ignition engine needs to fire spark plugs: on modern cars they’re mounted on each plug or grouped in a coil pack on the engine; on older vehicles they sit near the distributor; on small engines they’re integrated with a magneto by the flywheel. Diesels and battery-electric vehicles don’t use them. Knowing your engine type and layout will lead you straight to the coils for inspection or service.

What do ignition coils look like?

Ignition coils vary, but modern versions often appear as a rubber-booted component sitting directly on a spark plug, while older vehicles might have a cylindrical metal canister coil with wires connected to a distributor system. Inside, they all feature an iron core surrounded by two sets of copper windings (a thick primary coil and a thinner, more numerous secondary coil).
 
Modern (Coil-on-Plug/COP) Ignition Coils 

• Appearance: A relatively small, often black, unit with a rubber boot at one end and an electrical connector at the other.
• Function: This boot slips over a spark plug, providing a direct high-voltage connection.
• Mounting: They typically mount directly on the engine’s valve cover for a clean installation and computer-controlled timing.

Older (Distributor) Ignition Coils 

• Appearance: A small, metal cylinder, sometimes called a “canister” type. 
• Connections: Wires sprout from it, including one for battery power, one to the distributor’s contact points, and the main high-tension wire to the distributor cap. 
• Function: This coil generates the necessary high voltage to send to the distributor, which then distributes the spark to the correct cylinder at the right time. 

Internal Structure (Common to All Types) 

• Iron Core: A central core made of small iron slabs. 
• Primary Coil: A few turns of thick copper wire wrapped around the core. 
• Secondary Coil: Thousands of turns of thinner, enameled copper wire, densely packed and insulated from the primary coil. 
• Insulator: The entire coil is encased in a resin insulator to prevent short circuits. 

This video shows the different types of ignition coils and their internal components: 1mspeedkar99YouTube · Dec 25, 2017

Where are ignition coils located?

Ignition coils can be located in a few different places, depending on the vehicle’s age and ignition system: they may be in the engine bay, mounted directly on the spark plugs in coil-on-plug (COP) systems, in a coil pack, or inside the distributor on older cars. To find the specific location for your car, you may need to remove a plastic engine cover and consult your owner’s or repair manual, according to Advance Auto Parts and CarParts.com. 
Older Vehicles (with Distributor)

• In older cars with a traditional ignition system, a single coil is often located in the engine bay and connects to the distributor. 
• On some older GM vehicles, the coil may be mounted directly on top of the distributor cap, like an HEI coil. 

This video demonstrates how to remove an ignition coil from an older vehicle: 53sebayYouTube · Jun 24, 2024
Modern Vehicles

• Most modern cars use a coil-on-plug (COP) system, where one ignition coil is placed directly over each spark plug. 
• You can typically find these by removing any plastic engine covers on top of the engine. 
• You may also find what’s called a wasted spark system, which uses coil packs mounted to the engine to fire pairs of spark plugs. 

This video shows how to replace a coil-on-plug system in a modern vehicle: 1mFCP EuroYouTube · Sep 11, 2022
How to Find the Coil in Your Car

1. Open the Hood: With the engine off, open the hood to access the engine bay. 
2. Remove Engine Covers: Look for any plastic covers or components of the air intake system that may be in the way and carefully remove them. 
3. Identify the Coils: Look for the individual coils mounted on the engine, usually over the spark plugs. 
4. Check Your Manual: If you’re still unsure, consult your vehicle’s owner’s manual or a repair manual for the exact location of the ignition coils. 

Where to find the ignition coil in a car?

In most cars, the ignition coil is directly connected to the spark plugs. You will be able to find the ignition coil in your car by opening the bonnet and looking at the top of the engine.

What are the symptoms of a failing ignition coil?

Symptoms of a failing ignition coil include a Check Engine Light, engine misfires and rough idling, stalling, loss of power, poor fuel economy, difficulty starting the engine, and exhaust backfiring or a smell of gas. These issues occur because the coil fails to deliver enough voltage to the spark plugs, preventing proper combustion. 
Common Symptoms

• Check Engine Light: A blinking or steady Check Engine light often indicates a misfire, which is a common sign of a failing ignition coil. 
• Engine Misfires/Rough Idling: You may notice a jerky or stuttering motion while driving, or the engine may feel unstable and vibrate when idling. 
• Stalling: The engine might cut off or stall when you come to a stop. 
• Loss of Power: The vehicle may feel sluggish, especially during acceleration, due to incomplete combustion in the cylinders. 
• Poor Fuel Economy: With less efficient combustion, your car will consume more fuel, leading to lower gas mileage. 
• Difficulty Starting: The engine may crank longer or fail to start altogether. 
• Exhaust Backfiring: You might hear a sputtering or coughing sound from the engine or tailpipe. 
• Smell of Gas: An incomplete combustion process can send unignited fuel into the exhaust, creating a gas smell. 

What’s Happening Inside the Engine
A failing ignition coil cannot provide the proper voltage to the spark plug. This leads to: 

• Incomplete Combustion: The fuel-air mixture in the cylinder doesn’t ignite correctly. 
• Misfires: The spark plug fails to do its job, causing the engine to misfire. 
• Engine Performance Issues: The misfires disrupt the smooth operation of the engine, resulting in the symptoms listed above.