What Is An Ignition Coil And Why Is It Important?

Ignition coils are pretty important parts in an internal combustion engine. Without ignition coils, your engine won't start or run. What's an ignition coil, though? Let's find out.

What’s An Ignition Coil?

You can find an ignition coil at the top of each cylinder. An ignition coil is a tube-shaped part. It has a laminated iron core, which is wrapped in copper wire.

OEM coil

Volkswagen ignition coil #07C-905-715-A: for 2002-2006 VW Passat and Phaeton

Most modern vehicles have ignition coils that connect directly to the spark plug. Older vehicles have a coil with a high-voltage cable coming out of the top. That cable connects to a distributor, when then distributes the high voltage current to each spark plug.

Why Does Your VW Have An Ignition Coil?

The purpose of an ignition coil is to take the low voltage current from the battery and then turn it into high voltage current. The battery doesn’t produce enough voltage for the spark plugs to create a spark. That's why there's an ignition coil in each cylinder.

A car battery can only produce 12 volts. A spark plug needs between 12K and 45K volts to fire properly. The ignition coil bridges that gap and enables the spark plug to ignite the fuel mixture.

How Does An Ignition Coil Work?

The ignition coil receives power as soon as the ignition switch rotates to the run position. The engine fires up as soon as you turn the ignition key to the start position. Turning the key kicks a chain of events into motion. Here's what happens:

  1. You start the car.
  2. The engine powers the alternator, which powers the battery.
  3. The battery powers the ignition system, including the coils.
  4. The powertrain control module tells each ignition coil when to fire.
  5. The ignition coil transforms the battery’s low voltage into a high voltage current.
  6. The high voltage current is transferred to the spark plug.
  7. The spark plug ignites the air/fuel mixture, therefore powering the engine.

Does An Ignition Coil Need Replacing?

Replace coil

Image Credit: Auto Repair Guys

Yes, you will probably need to replace your ignition coils during your engine's lifetime. An OEM ignition coil typically lasts about 100k miles or more. But, sometimes they fail sooner than that. If one of your ignition coils fails, you'll notice some of these symptoms:

  • Backfiring
  • Stalling
  • Rough idle
  • Sluggish acceleration
  • Decreased fuel economy

You could get away with not replacing a bad ignition coil for a while. But it'll cause long term damage to the engine and the exhaust system. So that's why we always recommend replacing your bad ignition coil as soon as possible.

At VW Parts Vortex, we carry OEM ignition coils at rock bottom prices. In fact, we offer a price match guarantee. That means you'll get the best prices with us. Check out our catalog of VW ignition coils today!