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Weak Ignition Coil Symptoms

As a car owner, you rely on your vehicle to get you to your destination safely and smoothly. However, if your car’s ignition coil is failing, it can cause a range of problems that can compromise your vehicle’s performance, fuel efficiency, and even safety. In this article, we will discuss the most common weak ignition coil symptoms and answer some frequently asked questions to help you understand the issue better.

What is an ignition coil, and how does it work?

An ignition coil is a component of your car’s ignition system that transforms the battery’s low voltage into high voltage needed to spark the spark plugs. The spark plugs, in turn, ignite the air-fuel mixture in the engine’s cylinders, creating the power that propels your car forward. Without a functioning ignition coil, the spark plugs won’t fire properly, leading to engine misfires, stalling, and other problems.

What are the signs of a weak ignition coil?

weak-ignition-coil-symptoms 2

1. Loss of power:

If you notice that your car feels sluggish and unresponsive, especially when accelerating or climbing hills, it could be due to a weak ignition coil. The irregular sparks produced by the failing coil can’t deliver the necessary combustion, leading to a loss of power.

2. Check engine light on:

When your car’s check engine light illuminates, it’s a sign that your car’s computer has detected a problem with the engine’s performance. A malfunctioning ignition coil can trigger a misfire, causing the check engine light to come on. If left unaddressed, the issue can lead to more serious engine damage and costly repairs.

3. Poor fuel economy:

If you find yourself visiting the gas station more often than usual, even if you drive the same distance, it could be due to a weak ignition coil. When the coil fails, it can cause an incorrect oxygen sensor reading, leading to the fuel system injecting more gas than necessary to compensate for the lack of power in the spark plugs. This can decrease your car’s fuel efficiency and increase your expenses.

4. Backfiring:

If you hear a loud bang sound, see black smoke coming out of the exhaust pipe, or smell gas when your car starts to backfire, it’s a sign of a bad ignition coil. The unused fuel in the combustion cylinders explodes, causing a backfire and potentially damaging the engine.

5. Misfiring engine:

When your car’s engine misfires, it means that one or more cylinders are not firing correctly, or not at all. A weak ignition coil can cause the spark plugs to fire erratically or not fire at all, leading to a misfiring engine. If left unchecked, a misfiring engine can cause damage to the catalytic converter and other engine components.

6. Hard starts and stalling:

One of the weak ignition coil symptoms is hard starts and stalling. When the ignition coil is weak, your car’s engine may have difficulty starting or not start at all. If you turn the key and experience no response or your car stalls when you stop or idle, it’s possible that the issue is due to a faulty ignition coil that is not providing the necessary voltage to the spark plugs.

7. Spluttering and coughing sounds:

If you hear unusual sounds like spluttering or coughing when you start the engine, it’s a sign that an ignition coil is failing. The sounds come from a cylinder that is not firing at all during the ignition process, leading to rough starts and poor engine performance.

8. Jerking and vibrating:

Another sign of a weak ignition coil is when your car jerks or vibrates when idling or accelerating. The irregular sparks can cause hesitation and a lack of power, leading to jerking and vibration.

What should I do if I suspect a weak ignition coil?


If you suspect a weak ignition coil, it is important to act fast to prevent further damage to your vehicle. Here are the steps you can take:

1. Check for symptoms:

Look for any of the symptoms we discussed earlier, such as loss of power, poor fuel economy, backfiring, misfiring, hard starts, spluttering and coughing sounds, or jerking and vibrating. If you notice any of these symptoms, there’s a good chance that your ignition coil is weak or failing.

2. Perform a visual inspection:

Check the ignition coil for signs of damage, such as cracks or corrosion. Make sure the connections are tight and clean, and check the spark plug wires for signs of wear.

3. Use a diagnostic tool:

If you have a diagnostic tool, connect it to your vehicle’s OBD-II port to read any trouble codes that might be present. If you see a code related to the ignition system, there’s a good chance that your ignition coil is causing the problem.

4. Consult a professional:

If you’re not comfortable performing these checks or don’t have the necessary tools, it’s best to consult a professional mechanic. A qualified Cadillac technician can perform a more thorough diagnostic test and recommend the best course of action.

5. Replace the ignition coil:

If it is determined that your ignition coil is weak or failing, it will need to be replaced. A qualified mechanic can do this for you, or you can do it yourself if you’re comfortable working on your vehicle. Be sure to use a high-quality replacement ignition coil that is designed for your specific make and model of vehicle.

Related: How Long Does an Ignition Coil Last

FAQs about Weak Ignition Coil Symptoms

Q: How much does it cost to replace an ignition coil?

A: The cost of replacing an ignition coil can vary depending on the make and model of your vehicle, as well as where you live and where you take your vehicle for repairs. On average, you can expect to pay anywhere from $120 to $400 for parts and labor.

For example, let’s say you have a 2010 Cadillac CTS and you take it to a dealership in Los Angeles for repairs. The cost to replace a single ignition coil could be around $250.

Q: Can a weak ignition coil cause damage to other parts of the engine?

A: Yes, a weak ignition coil can cause damage to other parts of the engine if left unchecked. For example, if the engine is misfiring due to a weak ignition coil, unburned fuel can enter the exhaust system and damage the catalytic converter. Additionally, a misfiring engine can cause excessive vibration that can damage other components, such as motor mounts or exhaust hangers.

Q: How often should I replace my ignition coils?

A: There is no set schedule for replacing ignition coils, as their lifespan can vary depending on a number of factors, such as the quality of the coil, the driving conditions, and how well the vehicle is maintained. Some experts recommend replacing ignition coils every 100,000 miles, while others suggest doing so every 50,000 miles or whenever symptoms of a failing coil appear.

For example, let’s say you have a 2015 Cadillac Escalade with 80,000 miles on the odometer. You haven’t experienced any symptoms of a failing ignition coil, but you’re curious if you should replace them preventatively. In this case, it may be a good idea to consult with a qualified mechanic to get their professional opinion.

Q: Can I drive my car with a weak ignition coil?

A: It’s generally not recommended to drive your car with a weak or failing ignition coil, as it can lead to more serious issues and potentially leave you stranded. A weak ignition coil can cause your vehicle to misfire, which can damage other engine components or even cause the engine to shut down while you’re driving.

For example, let’s say you’re driving your 2012 Cadillac SRX and you notice that it’s hesitating and jerking when you accelerate. These are symptoms of a weak ignition coil, but you decide to keep driving the vehicle anyway. If the ignition coil fails completely, it could cause the engine to stall out in traffic or on the highway, which could be dangerous. It’s best to address the issue as soon as possible to avoid these types of scenarios.


In conclusion, being aware of the weak ignition coil symptoms can save you from costly repairs and ensure your vehicle is running smoothly. Loss of power, check engine light on, poor fuel economy, backfiring, misfiring engine, hard starts and stalling, spluttering and coughing sounds, and jerking and vibrating are all signs that your ignition coil may need attention. If you suspect an issue with your ignition coil, it’s important to act fast and seek the help of a qualified automotive technician.

Thank you for taking the time to read this article on weak ignition coil symptoms. We hope it has been informative and helpful. Remember to visit bradscartunes.com for more valuable insights and updates on automotive, truck, and car engines. Keep your vehicle running smoothly and enjoy a safe and comfortable ride!

Timothy Ballard

I’m Timothy Ballard, owner of a used car dealership in Springfield. I love just about everything automotive, but I have a special place in my heart for trucks. I’m an ASE Certified Master Technician, so I know my way around a car. In my spare time, I enjoy traveling with my family and hiking new trails.

1 thought on “Weak Ignition Coil Symptoms”

  1. 8 Signs of a Faulty Ignition Coil

    1/Your Car Guzzles Gas. …
    2/Your Car Feels Slow. …
    3/You Hear Spluttering, Coughing, and Banging Noises. …
    4/Your Car Idles Roughly and Vibrates. …
    5/Your Car Misfires and Backfires. …
    6/Your Car Stalls. …
    7/You Struggle to Start Your Car. …
    8/The Check Engine Light Is On.


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