Identifying Ignition Coil Failure Causes And Symptoms

Understanding Ignition Coil Failure Causes and Symptoms

The ignition coil is a critical component of a vehicle’s ignition system, responsible for transforming the battery’s low voltage into the high voltage necessary to create an electric spark in the spark plugs, which ignites the fuel-air mixture in the engine. When the ignition coil fails, the vehicle’s performance can be severely impacted. Understanding ignition coil failure causes and the most common failure symptomss can help drivers diagnose and address the issue before it leads to more significant engine problems.

The Most Common Causes Of Ignition Coil Failure

1) Worn Spark Plugs

As spark plugs wear, their gap increases, and that

Running too long on worn spark plugs can cause other, more expensive damage. These ignition coils were damaged by worn spark plugs.

larger gap requires a much higher voltage to jump the larger gap. When an ignition coil is forced to produce peak voltage for extended periods, it overheats, which degrades the insulation on the windings. That causes the ignition coil to fail.

2) Worn spark plug wires are the #2 cause of ignition coil failures

As spark plug wires break down, their resistance to electrical flow increases. When the ignition coil fires, much of the energy of the firing voltage is lost due to the increased resistance. Just like worn spark plugs, this higher voltage required to fire the plug increases the core temperature of the coil winding, causing it to fail.

In addition to conductor breakdown, the insulation on spark plugs also breaks down, allowing the spark to fire through the insulation to the nearest ground point. Arcing causes the ignition coil to overheat and fail.

#3 Heat is the #3 cause of ignition coil failure

The wire windings inside the coil are coated with thin lacquer insulation and the winding bundle is usually encased in epoxy. Prolonged exposure to high heat can cause the epoxy to break down, which results in internal arcing and failure.

Ignition Coil Failure Symptoms

1) Engine Misfires— One of the most common symptoms of a failing ignition coil is engine misfires. When the ignition coil can’t deliver sufficient voltage to the spark plugs, the fuel-air mixture may not ignite properly in the engine cylinders. This incomplete combustion results in engine misfires, which can cause the vehicle to run rough, especially under load or during acceleration. Drivers may notice a rough idle or jerking or sputtering sensation, particularly when driving at higher speeds.

2) Check Engine Light With Misfires Code(s)— A malfunctioning ignition coil often triggers the vehicle’s onboard diagnostic system, causing the check engine light to illuminate. This warning light can indicate various issues, but if it coincides with other symptoms like engine misfires or difficulty starting the engine, it strongly suggests a problem with the ignition coil. A flashing check engine light indicates a misfire that’s serious enough to damage the expensive catalytic converter.

3) Poor Fuel Economy— An ignition coil can fail completely or partially. A partial failure results in lower voltage and a much weaker spark, which causes poor combustion, low power, and poor fuel economy.

4) Difficulty Starting the Engine— A failing ignition coil can make it difficult to start the engine, particularly in cold weather or after the vehicle has been sitting for an extended period. The ignition coil is responsible for generating the spark necessary to ignite the fuel-air mixture. If the coil is weak or failing, the spark may not be strong enough to start the engine, leading to prolonged cranking or a no-start condition.

Backfiring— Backfiring occurs when unburned fuel ignites in the exhaust system, creating a loud popping sound. This can happen when the ignition coil fails to deliver a spark at the correct time, causing the fuel-air mixture to ignite late in the combustion cycle. While backfiring can have several causes, a faulty ignition coil is one potential culprit, especially if it occurs along with other symptoms like misfires or rough idling.

Loss of Power— A vehicle with a failing ignition coil may experience a noticeable loss of power, particularly during acceleration or when climbing hills. The engine may feel sluggish or unresponsive, as it is not receiving the necessary spark to perform optimally. This loss of power can make driving more challenging and may even lead to stalling in severe cases.

©, 2021 Rick Muscoplat