Should I Replace Ignition Coils With Spark Plugs? Detailed Answer

“Should I replace ignition coils with spark plugs” confuses many car owners when they have problems with the ignition system?

The replacement of damaged parts is obvious, but is it necessary to replace both simultaneously? What signs let you know it’s time to change?

Let’s explore this topic with us through the article below.

Are Ignition Coils And Spark Plugs The Same?

Should I Replace Ignition Coils With Spark Plugs?

First, to see whether you can replace spark plugs and coils, let’s look at these two devices.

The ignition coil and spark plug are two important parts of a car’s secondary ignition system. Most modern vehicles use these coils to provide the spark to the spark plug.

It uses electromagnetic induction to convert an electrical current of 12V into a spark powerful enough to shoot through the gap of a spark plug (several thousand volts).

Its function and way of operation are quite simple, but it plays an important role in ensuring the operation.

Over time, this part can burn out, fail, increase resistance levels, and many other problems.

As a result, it distorts or reduces the intensity of the spark, reduces ignition efficiency, and impedes engine performance.

When it is working poorly or not, this will cause the spark plug to fail, which means the car will lose one or more cylinders. The symptoms of a failed igniter are similar to those of a failed spark plug.

Should I Replace Ignition Coils With Spark Plugs?

Two devices work closely together, so when one fails, the other can hardly function properly. Thus, changing coil packs with spark plugs is a must, not mandatory.

As mentioned above, they are two of the many essential components that make up the electronic ignition system in a car.

This system plays an important role in the carburetor combustion process to generate energy for the vehicle.

When it is working efficiently, the air-fuel mixture is maximized, and your car will be able to operate more smoothly.

Achieving this requires smooth coordination of all ignition system components: power supply/battery, ignition coil, switches, modules/controllers, sensors, contacts, and spark plugs. For example:

The coil takes on the role of converting incoming current into a new draft. Its power must be large enough that a spark can be generated through the gap of the last part of the system – the spark plug.

At this time, the spark plug generates a spark to ignite the original air-fuel mixture, helping the engine to operate.

What Signs Indicate When To Change Ignition Coils?

What Signs Indicate When To Change Ignition Coils?

When it degrades or stops working, it will affect the operation of the spark plugs, the ignition system, and even the entire engine.

Thus, detecting symptoms early when a breakdown begins is extremely important. Be careful with the following signs:

Strange Smell, Black Smoke

The first sign of the bad coil is that the exhaust through the exhaust has a strong odor and is black.

This phenomenon occurs because the spark is not strong enough to completely ignite the fuel in the cylinders. As a result, unburned fuel is mixed in the exhaust gas, causing black smoke.

Consume More Fuel

There can be many reasons a car “eats” more fuel than usual, and ignition coil failure is one of them.

Since it is not possible to completely burn the fuel, the engine must pump more energy into the combustion chamber to ensure the operating pressure.

Shake The Engine, Change The Speed

The voltage generated by the faulty coil is not large enough, causing the engine to be reduced in power, losing fire, leading to jerks, vibrations, and stalled or variable speed (Engine Misfires phenomenon).

Sudden Shutdown

For combustion to occur in an automobile engine’s cylinder combustion chamber, three elements are needed: gas, fuel, and spark.

When the spark plug has a problem, the spark will be weak, ignite at the wrong time or not generate the spark.

This greatly affects the combustion of the gas and fuel mixture, causing the vehicle to stall or stall.

The Engine Is Hard/Won’t Start

Malfunctions can cause loss of power in some or all cylinders, reducing/reducing work output. This makes diesel engines difficult to start or even impossible to create.

Check Engine Light Flashing

One of the reasons why the error light comes on may be due to the igniter. At this time, the driver should bring the car to an auto repair shop to check and fix it in time.

How Often To Replace Ignition Coils?

How Often To Replace Ignition Coils?

As an integral part of the car engine system, it significantly influences the vehicle’s operation.

After a period of use, this part is inevitably damaged. The replacement of defective parts is essential to ensure operation.

However, the ignition coil has a limited lifespan, just like any other engine part.

At the end of the manufacturer’s recommended service life (available on the specifications), vehicle owners should replace the coils to ensure improved performance.

The right time to change is usually when the car has run about 190,000 – 240,000km.

Car owners can ask an auto mechanic to check these coils’ functioning during vehicle maintenance to determine the most accurate time.

What Does The Replacement Cost?

A normal coil-on plug one usually costs a few hundred dollars, and a cassette-style system can go up to $1000. The cost of repair is high or low, depending on the type you choose.

You can extend the coil life by replacing the spark plugs periodically as specified by the manufacturer. This helps you promptly deal with small oil leaks, preventing coil wear.

However, malfunction is inevitable no matter how well maintained.

At this point, available aftermarket ignition coils are a more economical option, but beware, as their quality may not be as good as the original manufacturer’s equipment.

Is It Safe To Drive With A Bad Ignition Coil?

When one or more windings begin to fail, it can become a major challenge for your motor’s operation.

The defective part will not be able to utilize the amount of gasoline entering the exhaust system fully. The ignition engine’s failures after a long use time affect the oxygen sensor and the catalytic converter.

That is why you should not continue driving when you see abnormal signs in the system and the coil.

Your car may not “die” right away, but the risk of an explosion will gradually increase if you deliberately continue to use it.


Do I Only Have To Replace One Coil Or All?

According to experts, car owners should replace auto parts in pairs, but you don’t need to replace all because they don’t come in pairs. Each cylinder has one, so a damaged one won’t affect the other locks either.

It would not be best if you replace coils that are still in good working order, as they have been thoroughly tested and determined to be compatible with the motor.

Using untested or incompatible new ones can degrade your vehicle’s performance.

Thus, when checking the coils and only finding a few working poorly or failing, you should not replace all of them; replace the faulty ones.

If service centers ask you to replace all coils, ask carefully why and only agree when you think it is reasonable.

Does The New Ignition Coil Help Improve Performance?

Yes. When it comes to car problems, many users often wonder if replacing new equipment can return the car to its original condition.

In this case, maintaining and replacing good quality ones will help regain lost performance.

If the problem is caused by faulty wiring, stuck spark plugs, winding down, broken distributor caps, etc., new ones will help to solve them, so everything is back to the way it was.

It improves fuel combustion efficiency by producing a more powerful electric spark and unbiased ignition timing.

Can I Check And Replace Them Myself? 

To check, it is necessary to use a scan tool to determine the trouble code showing which engine cylinders have failed and which windings are faulty.

Next, the maintenance specialist must check the ignition coil according to the manual procedure.

Typically, this procedure involves measuring the resistance between the terminals of the coil.

The resistor is out of spec, so you need to replace it soon. Since this requires professional measuring tools, it can be difficult for the uninitiated.

In addition, this part generates extremely high voltages that are dangerous to your health, so you must observe safety measures when working with it.

Don’t forget to disconnect the negative battery cable before checking or replacing it.

When you need to replace the ignition coil, you better bring the car to the repair shop to receive the help of professional mechanics.


Above is the information for the question: should I replace ignition coils with spark plugs?

You should, but if the spark plugs are still good, then you can consult a technician. Don’t forget to check regularly to detect and fix problems in time.

Wish you safe driving. Thanks for reading.

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