can bad ignition coil cause car not to start

by:Haiyan     2023-07-03

Can Bad Ignition Coil Cause Car Not to Start?


The ignition coil is a crucial component in a car's ignition system. Its primary function is to transform the battery's low voltage into the high voltage needed to ignite the fuel mixture in the engine cylinders. However, like any other part in a vehicle, the ignition coil can also experience issues over time. One common problem associated with a faulty ignition coil is the failure of the car to start. In this article, we will delve into the reasons behind this issue and explore the consequences of a bad ignition coil on a vehicle's starting process.

1. Understanding the Ignition Coil

a. Role of the ignition coil in the starting process

Before diving into the potential effects of a faulty ignition coil, it is essential to understand the role it plays in starting a car. The ignition coil acts as a power transformer, converting the low voltage from the battery into thousands of volts necessary to create an electric spark within the engine's combustion chamber. This spark ignites the air-fuel mixture, starting the engine.

2. Symptoms of a Bad Ignition Coil

a. Engine misfires

b. Rough idle

c. Decreased fuel efficiency

One of the most immediate signs of a faulty ignition coil is engine misfires. When the coil fails to deliver the required voltage to the spark plugs consistently, the engine may stumble or even stall, leading to rough idling and a decrease in fuel efficiency. These symptoms can gradually worsen, eventually causing the car to fail to start altogether.

3. Impact on the Starting Process

a. Inability to generate sparks

b. Failure to ignite the fuel mixture

A bad ignition coil can directly impact the starting process of a car. If the coil is not functioning correctly, it might fail to generate the high voltage required to produce sparks across the spark plugs properly. Consequently, there will be no ignition of the fuel mixture, resulting in the engine not starting at all.

4. Testing the Ignition Coil

a. Using a multimeter

b. Checking for resistance

To determine whether an ignition coil is the culprit behind a car's starting issues, it is necessary to perform a thorough testing procedure. One common method involves using a multimeter to measure the coil's output voltage. Additionally, checking the coil for any resistance inconsistencies can help identify whether it is functioning properly or not.

5. Replacing a Faulty Ignition Coil

a. Choosing the right replacement

b. Professional vs. DIY installation

Once symptoms of a faulty ignition coil are identified and confirmed through testing, it becomes crucial to replace the defective component. The market provides various options for replacement coils, making it necessary to select the one that matches the car's make and model. While replacing an ignition coil might seem like a simple task, it is worth considering whether a professional should handle the installation to ensure optimum performance and minimize potential risks.


A bad ignition coil can indeed cause a car not to start. As a vital component in the ignition system, it is responsible for generating the high voltage required to ignite the fuel mixture in the engine. Symptoms such as engine misfires, rough idling, and decreased fuel efficiency provide early warning signs of a problematic coil. It is crucial to troubleshoot and replace a faulty ignition coil promptly to avoid further damage to the vehicle's starting process. Seeking professional assistance in such cases can provide peace of mind and ensure a successful replacement, guaranteeing the car's long-term performance.

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