Home Diagnosis and TroubleshootingEngine Problems Ignition Coil Replacement Cost – Lighting Your Money On Fire?

Ignition Coil Replacement Cost – Lighting Your Money On Fire?

by Jordan Harris
Ignition Coil Replacement Cost

At the heart of every automobile is an engine, powered by a series of controlled, timed, and precise explosions. This combustion begins with a bright spark, igniting a concentrated mixture of fuel and air. From here, energy is created to propel your car into the sunset. Yet, and as reliable as the engine may be, it will soon come of age where the source of its combustion may wither away. That then, is why we’re taking a look at the ignition coil replacement cost, as yours is probably due soon.

But for such an important component, how could the ignition coil fail? Well, and as everything on a car does at some point, it goes through a lot of strain. Imagine the countless zaps of high voltage as it flows from the battery, and onto the spark plugs. As the one responsible for making this happen, the ignition coil could only take so much. For this vital piece of machinery, you might be surprised that the ignition coil replacement cost might not be as expensive as it seems.

What Do You Need To Know About The Ignition Coil?

Before we get into discussing the proverbial ignition coil replacement cost, it would help to know the function of the ignition coil. More importantly, what role does it actually play within the combustion process of an engine? As we mentioned earlier, the ignition coil is in a happy place between the car’s spark plugs and the battery.

As you might know, the spark plugs create a spark to ignite the compressed mixture of fuel and air inside the engine’s cylinders. When it combusts, this explosive force pushes the pistons up and down, hence creating rotational power. On the other side, the battery is what supplies the voltage required to enable that spark to light up in the first place.

However, the battery can’t simply connect directly to the spark plug. In doing so, the 12-volt battery can’t produce enough voltage for the spark plugs to work efficiently. In other words, the voltage is too small to create a large spark. With that in mind, we have the ignition coil. Its design remained similar for the last 100 years or so, in that the ignition coil acts as a transformer.

It boosts the steady 12-volt output of your car’s battery and ramps it up to 15,000, 20,000, or up to 30,000-volts. The actual voltage required will depend on your vehicle, and powertrain setup. Only with this sort of high voltage, could the electrical current be adequate enough for a large spark to be ignited. It does this through the magic that we call, electromagnetism.

How Does This All Work?

When electrical current flows through a conductor, such as a coil of wire, it creates a magnetic field around the coil. Otherwise referred to as a ‘magnetic flux’, it can effectively store and boost the total electrical output. On top of that, the ignition coil applies a concept known as a ‘collapsing magnetic field‘. Typically, the ignition coil would have two sets of winding coils.

Both are then connected to the positive and negative terminals of the battery. The primary winding can have anywhere between 150 to 300 turns of that aforementioned coil of wire. Meanwhile, the secondary winding commonly has 100-times that, around 15,000 to 30,000 turns. In practice, the magnetic field is generated when the battery sends all 12-volts through the primary winding.

When a spark is needed at the spark plug, the car’s ignition system will then switch off the current flow to the primary winding. Suddenly, this will cause the magnetic field to collapse. It will induce a voltage of around 200-volts by the end of the primary winding, which then crosses over. As a result, the secondary winding now has a voltage output approximately 100-times greater, at 20,000-volts.

This mutual inductance is what allows the secondary winding to have a significantly higher voltage output, which would be sufficient for the spark plugs to spark. Usually, the ignition coil wraps both the primary and secondary winding inside of an iron core. This helps to concentrate and enhance the strength of the magnetic field, making the ignition coil far more efficient.

What Are The Different Types of Ignition Coils That You Should Know?

An automotive ignition coil is engineered to last a long time, generally at least 100,000 miles or so. It commonly wears out over time due to the insulation wearing down. Or, it might fail prematurely over extended exposure to heat, moisture, poor wires, or a voltage overload. In all, though, ignition coil replacement cost is something you needn’t have to worry about all too frequently.

But when it comes time for you to think about that, then do be wary about what type of ignition coil your car uses. Starting with the basics, there are four types of ignition coils:

1. Conventional

These are old-fashioned and rely on a traditional breaker point-type ignition. The primary winding receives power from the battery through a resistor. It then flows to the distributor cap, before making its way to the spark plugs. However, these mechanical distributor ignition coils are inefficient. Plus, they’re not as durable, requiring a replacement every 12,000 or so miles.

2. Electronic

It’s mostly similar to the conventional system. However, instead of using a distributor cam and breaker points, it uses a pickup coil. This signals the control module to actuate the electrics. That said, and while it’s more reliable, it still relied upon input from the distributor shaft. The latter can develop gear wear after 120,000 or so miles, which could get in the way of proper spark timing.

3. Distributor-Less

An evolved version of prior designs, the distributor-less ignition coil system enables more energy to be strapped together from multiple coils. This ‘coil pack‘ of several ignition coils uses a magnetic triggering device to determine the engine speed and crankshaft position. Once analyzed, it can evaluate the best spark timing for the most efficient combustion.

4. Coil-On-Plug

The latest evolution of ignition coils, the coil-on-plug design incorporates all the electronic controls of a distributor-less ignition. That said, instead of two cylinders sharing a single coil, each coil-on-plug services just one cylinder. You no longer need spark plug wires too, as they can often be mounted directly onto the spark plug. It’s much more powerful, with outputs as high as 50,000-volts.

What Are The Symptoms Of Failing Ignition Coils That You Need To Look Out For?

car won't start but battery is good

But… How could you tell that your ignition coil is on its way out? Well, there are a few symptoms that you could look out for to see if you need to think about an ignition coil replacement cost. Still, just know that not all of these tell-tale signs could trace its issues back to a faulty ignition coil. Some might be caused by too little or too much voltage from the battery.

Nonetheless, we can at least narrow them down to it potentially being a concern with the ignition coil. The symptoms will vary depending on how poor your ignition coils are, be they just about worn out, or have completely failed. Here are some of the most common signs of a bad, or failed ignition coil…

1. It’s Hard To Start The Car

First thing’s first, you’ll find it hard to start up the car with a bad ignition coil. If you turn the key, and there’s not a single sound coming from the engine bay (not even a click), then that’s a clear warning that something’s amiss with your car’s ignition system. More often than not, this symptom would be prevalent in older cars that have only a single ignition coil for every cylinder.

If so, then these cars fitted with a single ignition coil won’t start up at all if the coil has failed. Should you drive a more modern car that has multiple ignition coils, the engine might at least come to life. Although, it won’t be a smooth and effortless start-up process. Bear in mind that if you hear a ‘click’ sound, then the problem isn’t to be found on the ignition coil.

2. The Check Engine Light Appears

Your car’s check engine light may blink should it find a fault within the ignition system. That’s since the ignition coil has a direct effect on the engine’s operations, it being a crucial part of the ignition. If the check engine light does flash, then you could have it checked to see if the ignition truly is the cause for it to appear.

Scanned using an OBD diagnostics tool, you could check for error codes that could point you towards the source of the check engine light flashing at you. To be more specific, the ‘P0351’ error code is made just for the ignition coil, displaying a message similar to “Ignition Coil – Primary/Secondary Circuit Malfunction”.

3. Your Engine Might Misfire

Should you be able to start up your car anyways, you may or may not notice that the cylinders are misfiring. If this happens, then you may point the blame towards a faulty ignition coil. It may not have failed just yet, but it surely isn’t in good working order. As it’s now defective, the ignition coil might not be able to deliver enough voltage to the spark plugs, and it can’t do this smoothly.

Consequently, your cylinders might misfire if there’s too much or too little voltage which has been generated by the ignition coil. This happens as the spark timing is off, and the combustion process can’t be completed in the right manner. A misfire can sound like your car’s coughing or is barely sputtering to life.

4. Your Car Might Backfire

How Hot Does A Car Exhaust Get?

In automotive terms, ‘backfire’ can be defined by the combustion of the fuel-air mixture happening somewhere outside of the cylinder. This is quite serious, as it could result in catastrophic damage to your engine and exhaust system. Backfires could also occur as there’s a remnant of unused – read: unburnt – fuel left in the combustion chamber.

This then flows out of the cylinders, and into the exhaust pipe. You could tell by the plumes of black or dark smoke emitted out of the exhaust pipe. You might also smell a lot of gasoline in that smoke, just as pungent as a fresh fuel stop. In any case, backfiring could be attributed to a faulty or failed ignition coil. Put off repairs for long enough, and the damage can get really expensive down the line.

5. The Engine Might Stall

Going back to our thesis of the ignition coil maintaining steady combustion, its failure could prompt your engine to stall. This will happen, as a bad ignition coil will induce an irregular amount of voltage to ignite the spark plugs. With unreliable sparking, the engine can’t maintain the combustion for much longer, causing the engine to shut down in the middle of the road.

Usually, this is more common in older cars with a singular ignition oil, as we’ve discussed earlier. Newer cars, with more than a few ignition coils wrapped together, could at least keep the car going if one fails, albeit not smoothly. With just a single ignition coil, you might be able to start the car up again. However, the stalling is an indicator that the ignition coil won’t last long as-is.

6. Your Car Might Jerk, Idles Roughly, Or Has Poor Performance

If the ignition coil is knocking on death’s door, then you can surely expect poor performance from it. As it likely can’t deliver a sufficient amount of voltage to the spark plugs, you’ll feel its side effects when you’re behind the wheel. The car might jerk around, as the ignition coils could routinely fail or come back online again from one cylinder to the next. This shuddering can be annoying.

Or, it might idle very roughly, as the ignition coils are barely able to sustain the voltage needed to keep the engine lit up. Last but not least, and even if your car could still move, it might be down on power. With newer cars, having one or more ignition coils failing means there are fewer cylinders at work in the engine. You could notice significant hesitation when accelerating.

7. Your Fuel Economy Would Be Poor

Poor fuel economy can be blamed for any number of reasons. Among them would be a faulty ignition coil. All those symptoms up above, such as misfiring, backfires, jerking, rough idling, or just very poor performance, can take a chunk out of your fuel tank. A bad ignition coil requires the engine to work harder, and burn more fuel than it’s really necessary.

Then, we’ll have to contend with all those issues and inefficiencies, such as poor spark timing. Or, it might be the ignition coil burning away the fuel through half-hearted bursts of volts to the spark plugs. Thus, a faulty ignition coil may prompt you to fuel up more often (just make sure you don’t accidentally put gas in your car while it’s running).

Should you notice an increase in fuel consumption, then we should give the ignition coils a check.

How Much Does The Ignition Coil Replacement Cost For Your Car?

Finally, we can get into the meat of our guide here – how much does an ignition coil replacement cost? As we answer that, remember once again the varying configurations of ignition coils. Some cars may have one ignition coil for each spark plug, which is common for newer cars. These could sit right on top of the spark plug or may need connecting with a spark plug wire.

Alternatively, your car – often older models – may have a single ignition coil pack for every cylinder. Therefore, the price will vary depending on what type of ignition coil you’re looking for. And, we’ll have to factor in the make and model of your vehicle. A higher-end vehicle made for heavy-duty work or sporty driving should require ignition coils that could deliver a steady stream of high voltage.

These units would carry a pricier cost compared to a set of ignition coils for your typical economy car. Moreover, we’ll have to consider the cost premium of having your ignition coils replaced at a certified dealership over an independent workshop. By comparison, the former will guarantee the use of OEM parts but costs a whole lot more in charges and labor fees.

The Cost Breakdown:

Parts – The actual ignition coil itself can commonly be found for around $70 to $375 apiece. It may cost more depending on the type of coil, as well as the make and model of vehicle that you’re fitting it into. OEM parts from your vehicle’s manufacturer will cost more, but you could certainly get away with using aftermarket ignition coils, should they be compatible with your car.

Labour – A professional installation of the ignition coils should take no longer than 0.5 to 1.5 hours. This is thanks to the ease of getting at the ignition coils themselves, which are placed right at the top of the engine. We can then calculate the total ignition coil replacement cost, by tabulating the labor rates at $50 to $120 per hour on average.

In total, we can estimate that the ignition coil replacement cost rounds up to somewhere between $100 to $550 for most cars. For the lot of you out there, you can expect it to land around $200 to $300. While you’re already at the workshop, you might also consider some additional inspections, too. For example, have a technician look at the coil wires, spark plugs, and spark plug wires.

Over time, these too could fail. Exposure to heat can cause them to crack, or they could be suspect of corrosion. If you need to replace them, you could safely add another $50 to $350 to the final ignition coil replacement cost. It’s a good idea to look at these components as well while you’re replacing the ignition coils, as it’ll save you from having to book another trip to the workshop later on.

Could You DIY This Fix To Save On The Ignition Coil Replacement Cost?

If you’re keen to avoid the pricy labor charges, then you’d be happy to hear that replacing a car’s ignition coils is one of the most DIY-friendly fixes that you can do. If you don’t mind getting a bit of grease on your clothes, then this is surely one repair job that you could manage at home. Even for the rookies, swapping out the ignition coils is a great way to get into DIY-ing for the first time.

The tools you’ll be needing are:

  • A new ignition coil
  • Screwdrivers
  • Socket set and ratchet
  • Wrenches
  • A service manual for your car

A Step-By-Step Guide On Replacing Your Ignition Coils

Step 1: The first thing you should always do when working on your car is to disconnect the battery. You can use a socket or wrench to detach the clamp bolt holding the cable to the terminal.

Step 2: Next, try and find the ignition coils. Referring to your car’s service manual could be handy, but you can usually find them at the very top of the engine. They could be attached to the engine block or its surrounding components.

Step 3: Now, disconnect and remove the old ignition coil. They are attached to the vehicle using either bolts or screws. You’ll also have to remove the electrical connectors from the coil, as well. Take a peek at your service manual, and see in which order should you do first… To remove the electrical connections, or to unbolt the unit.

Step 4: Once you’ve figured it out, unbolt or unscrew the ignition coil and its electrical connections in the right order. Although, do remember that some cars have a single ignition coil powering several spark plugs at a time. In this scenario, you’ll have to mark down which electrical connectors go where for reassembly. For it to work, you have to reattach the connectors in the corresponding terminals with the new ignition coil (be wary of the differences between the ignition coil vs spark plug).

Step 5: After you’ve gotten the old coil out of the way, you can install the new unit in there. Do everything in reverse order, and remember, reconnect the connectors back to their correct terminals onto the new coil. Also, be sure to not overtighten the bolt or screw.

Step 6: At this stage, you can start the engine up. With the vehicle in ‘Park’, check and see if your car idles smoothly and normally. If all’s well, then you could go for a short test drive.

Ignition Coils: What They Are, How They Work, and How to Tell When They’re Bad

  1. Ignition coils transform a small electrical charge into high-voltage energy to ignite the air-fuel mixture in a combustion chamber.
  2. The battery’s 12 volts cannot provide a dependable spark, so an ignition coil elevates the spark to 25,000-30,000 volts.
  3. Early models used conventional ignition coils with points, while modern cars use coil-on-plug design, where each cylinder has its own coil.
  4. Ignition coils use electromagnetism to multiply an incoming electrical current to a much more powerful current when it leaves.
  5. Symptoms of a bad ignition coil include a check engine light, engine misfiring, higher emissions, lower fuel efficiency, and difficulty starting the engine.
  6. Coil-on-plug ignition coils can be tested quickly and easily with a scan tool by swapping coils from one cylinder to another.
  7. The cost to replace an ignition coil ranges from $35 to $300, depending on the vehicle.
  8. Labor costs for replacing an ignition coil are minimal as the coil is typically easy to access.
  9. Some people choose to replace the ignition coil themselves to save on labor costs.
  10. After replacing an ignition coil, the check engine light will need to be cleared using a scan tool.

Ignition Coil Replacement Cost – Conclusion

In all, we can conclude that the ignition coils are vital to the inner workings of your car. Without it, your beloved car might not even start. Therefore, it’s good to know that ignition coils are made to be robust and dependable. With plenty of cars out there, they could possibly last throughout the entire ownership period. Yet, you may still have to come across paying the ignition coil replacement cost.

For all its importance, ignition coils are surprisingly not the most expensive things to repair on a car. A bill of around $100 to $500 – or just $70 to $375 for the coil itself – isn’t too damaging to your bank account. Plus, you could pile on a huge saving in labor charges by replacing them yourself. Ignition coil replacement cost is, by all accounts, a not-so-bitter pill to swallow.

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