Do ignition coils go bad at the same time & should I replace them at once?

Ignition coils are complex components used for creating sparks for spark plugs. They are controlled electronically, and there are various reasons why they could malfunction. When they stop working, one or more engine cylinders can experience a loss of spark. It is a serious problem. 

These coils are a new addition to modern vehicles and have a reduced risk of catching fire. It is because they do not feature any moving parts. Therefore they are more reliable than the classic distributors. By creating stronger sparks for cleaner combustion, they perform better than distributors.

These parts do a better job of creating a good spark, allowing for better combustion and increasing your vehicle’s performance. Maybe you are wondering if ignition coils go bad at the same time and whether you should replace them all at once. We got you covered with an insightful answer below. 

Table of Contents

GM V-8 ignition coils

What causes a coil pack to go bad?

There are several reasons why a coil pack could fail. Heat, vibration, or other issues unrelated to the ignition system could make these parts go bad. They are installed on the cylinder head and can be found at the top. 

When exposed to heat and vibration, the insulating material will break down over time and create an internal coil failure. When ignition components are worn, they will cause a coil to work harder and deliver more voltage. 

Here’s a more comprehensive list of what will make them go bad:

  • Excessive, continuous heat
  • Moisture from an oil leak
  • Water intrusion
  • Excessive gap

With such an overpowered operation, the life span of your coil packs is significantly reduced. Once a single part fails, the electricity created will not be able to reach the spark plug. A failed ignition coil can also damage the engine computer or the control module. It is crucial to fix this problem as soon as possible. 

Do ignition coils go bad at the same time?

Not all of them can go bad at the same time. There is no way that a broken ignition coil will affect the others. You should not replace all the ignition coils at once. One pack is intended for two engine cylinders, and you should only change the faulty one. 

If they are in good shape and working properly, replacing them can be a big mistake. Old ones are better and more reliable than brand-new ones that haven’t been used yet. But because they are durable components, you should expect a long lifespan from these parts.

The most common reason ignition coils fail is bad spark plugs or plug wires. Sometimes, these parts can fail sooner than you expect if the fuel mixture is too rich or too lean. Vibrations and heat generated by the engine will also lower their lifespan. 

OEM m54 ignition coils

How often should ignition coils be replaced?

As a general rule, the ignition coils on your car should last for around 100,000 miles, but this mark can easily be exceeded. However, there are many factors to consider before replacing them. You should not replace them just because you reached this recommended mark. 

Instead, consider getting new ones only after you experience engine misfires or other symptoms signaling a problem with this part. They are very rare. Depending on the market, they can also be expensive.

When they fail, you will also have reduced gas mileage. Because they can transfer less power, your car will need additional fuel to run. In the long term, you will have to spend more money on fuel until you replace these parts. 

Should I replace all ignition coils at once?

GM V-8 ignition coils round style

Because they are so strong and durable, these packs should last for the entire lifetime of a vehicle. But when one of them goes bad, you don’t have to replace the entire system. While it is not mandatory, most people prefer to replace all of them if one fails after the car has more than 75,000 miles on board.

Wait until they show symptoms and only change ignition coils when they go bad. With proper maintenance, they will last you a long time, and you won’t have to worry about replacement costs. Consult a mechanic, and they will give you the best advice tailored specifically to your vehicle’s condition. 

Here are other components with roughly the same fix or replacement cost.

Car PartCost to Fix or Replace
Alternator$300 – $600
Battery$50 – $200
Fuel Pump$300 – $800
Ignition Coils$200 – $400
Mass Air Flow Sensor$200 – $400
Radiator$300 – $700
Serpentine Belt$50 – $150
Starter Motor$200 – $500
Throttle Body$150 – $350
Water Pump$200 – $450

Can you replace only one ignition coil?

It is possible to replace only one ignition coil if you notice that it is faulty. When you do it, you should also replace the spark plugs with the coils so you won’t have to remove them twice. Mechanics might suggest changing all the coils when one becomes faulty, but the decision is yours.

If you listen to their advice, you should ask them about the reasons behind changing each of them. Make your assumption and make the best decision based on the facts. 

Your car will experience several malfunctions, such as engine misfiring, which happens when you accelerate. In some severe cases, your car can shut down completely while driving. When this happens, you become a danger to other drivers and should pull over to the side of the road. 

Because one of the cylinders fired incorrectly, the misfire led to a complete engine shutdown. Replacing your ignition coils is crucial now, and you cannot drive your car before you fix this problem. Seek the help of towing services that will transport your car to the nearest auto repair shop. 

If your budget is tight, replacing the broken part will solve your problem. But because the repair shops will also charge for labor, most people choose to replace all of them. 

Coil ignition toyota

Should I replace ignition coils with spark plugs?

If these parts fail, the spark plugs cannot function properly. They are two separate parts that rely on each other. Most people also decide to replace the spark plugs when installing new ignition coils on their vehicles. If spark plugs are too worn out, they can create unnecessary loads on the coils. 

It is strongly recommended to replace both components at the same time if the spark plugs are the cause of ignition coils failing. However, replacing them is unnecessary if you are replacing the spark plugs during routine maintenance. Remember, ignition coils should always be replaced only when they are failing. 

If the system also features plug wires, replace them if they are worn or damaged. While replacing these broken components is a fix to your problem, you should also consider its cause and eliminate the source before more issues appear. 

Contact a mechanic and ask them about replacing these parts with spark plugs. Let them inspect your car and diagnose any possible problems. They will determine whether you should replace both of these parts or only the spark plugs. 

Are all ignition coils the same?

These parts are not always the same as they come in various shapes and sizes. You will find out that the distributor-type ignition system relies on one or more ignition coils to jump the spark plug gap and efficiently ignite the fuel mixture. 

New ignition coils will feature designs that are more specific to their applications. However, some universal options are still available. You can find the canister-type coil in breaker-point ignition systems. It is a popular design among manufacturers because they are easier to make.

But their shape and size are always identical. The only way manufacturers differentiate each other is through the labeling applied on the side. Before purchasing a replacement, you should ensure this part is compatible with your car. 

ENA

Here’s an example of one that works with various car models.

NameENA Ignition Coil Pack
Compatible withToyota & Lexus
Installation TypeBolt-On
Item Dimensions LxWxH9 x 3 x 6 inches
Item Weight‎9.6 ounces

Pros

  • They have hundreds of positive reviews.
  • It works for a Lexus & Camry.
  • Installation is easy.

Cons

  • It doesn’t work for every car.
Sale
ENA 
741 Reviews
ENA 
It works for a variety of models.
VW ignition coils

How to tell if a coil pack is bad

It is not difficult to test whether the coil packs need to be replaced. You have to ensure they are properly working and you can do this whenever you perform a routine maintenance inspection. Use an Ohm meter to test the,m but don’t forget to approximate the tool values according to the ignition coils.

Check the owner’s manual to find the values of your ignition coils. The manufacturer should specify this information. If you cannot find the manual, search your car model online and seek help from other owners that drive your type of vehicle.

Additionally, you can tell if it is bad just by noticing the symptoms. Some of the most common signs of a bad coil pack are:

  • Noticeable lack of power
  • Louder engine
  • Blinking check engine light
  • A significant drop in RPMs when accelerating
  • Rough idle
  • Smoke from the exhaust 

Will a bad coil pack throw a code?

Several signs will warn you about this part’s poor condition when a coil pack goes bad. For instance, the check engine light will come on as it detects the problem. The car computer knows when something goes wrong. In some newer models, it will also display a trouble code.

Additionally, you will notice that your car has increased emissions. If you do a state emissions inspection with a bad coil pack, your vehicle will not pass the test. Furthermore, you will be able to notice a reduced fuel economy due to incomplete combustion. 

If you have to refuel more often, take your car to a repair shop and have it inspected. That is why you should always prioritize this problem and fix it as soon as possible. 

Error codeDepartmentMost common reason
P0350Ignition coilMalfunction in a circuit
P0362Ignition coilCommunication issues in the electrical circuitry
P0300Engine misfireDamaged spark plugs
P0312Engine misfireDamaged spark plugs

What causes ignition coils to keep going bad?

Dodge 2006-2011 ignition coils

Ignition coils are durable parts designed to last a long time. However, they are not indestructible and will not last forever. Often, they fail because of bad spark plugs or plug wires. If your car’s fuel mixture is too lean or too rich, they will fail earlier than expected.

The heat and vibrations generated by the engine will speed up this process and shorten its lifetime. Wear and tear can happen to any engine block part, including the ignition coils. Their insulation will degrade and cause them to overheat. 

If conditions are ideal, they should last for the entire lifespan of your vehicle. If they break down eventually, you have to replace them immediately as your car will not function properly without them. 

FAQ


How long do ignition coils last?

Usually, ignition coils will last for the entire life of your vehicle. But in some cases, the engine’s exposure to vibration and heat will shorten their life. Considering several factors, you should expect coil packs to last up to 5 years or 100,000 miles before they need to be replaced.

Carbon accumulation can also damage them. You will have to replace this part eventually, but it doesn’t cost more than $300. The price still depends on the repair shop and considers the labor fees as well. 

However, their approximated lifespan does not mean you have to replace them once you hit that mark. Instead, only replace ignition coils when they go bad. 

Can ignition coils fail intermittently?

To run properly, your engine should have ignition coils that are in a perfect state. If one fails, the entire car will struggle, and your drives will no longer be as smooth as they were before. In some cases, the engine might stall if you reach certain speeds.

They are directly controlled by the engine control module, which is a highly performant device. It decides the timing of the firing of the spark plugs as well as their frequency. When an ignition coil goes bad, the engine timing will be delayed, and the entire performance of your engine will be greatly reduced.

But these parts can fail intermittently. They will also experience damage caused by the excessive vibration and heat coming from the engine. If bad spark plugs cause a voltage overload, these parts will suffer and lead to intermittent engine misfires. 

Ignition coil replacement cost

On average, you should expect to pay between $60 and $350 for replacing these parts. The price depends on the car model and does not include the labor costs. If you install these parts yourself, no additional costs are included.

But if you require a skilled mechanic’s help, they will charge you additionally for installing the piece. While a single ignition coil can range between $30 and $150, its installation costs between $30 and $200. 

While the replacement of an ignition coil is very easy, some car models have a more complex system and you will need professional help. That is why the replacement cost can be so high in some cases. If you are unsure about installing these parts, you should not proceed with this operation. You might cause additional problems that will cost you more money. 

Can a bad ignition coil cause rough idle?

It is true that your engine is the most affected once your ignition coils go bad. The entire performance of the car is greatly reduced, and the task of replacing these broken parts becomes a top priority. 
Suppose your car experiences rough idling, misfires, or a loss in power and acceleration. In that case, the problem can be strongly related to a failing coil pack. In some cases where the problem is more advanced, you will also experience stalling more often. 
Look for other symptoms and identify the problem by manually diagnosing the car. If you struggle with the mechanical part of your vehicle, seek professional help from an auto repair shop.