When Should Spark Plug Coils Be Changed?

The ignition system of a truck has various parts, but the spark plugs are popular. Spark plug coils are another essential part worth knowing. The spark plug coil has two coils, and it is this part where the electrical energy from the battery passes through to the spark plugs. The primary role of the spark plug coil is to transform the electrical energy from your truck’s battery into high voltage. It temporarily saves and emits the high voltage current to the spark plug.

The spark plug coil, just like other parts of the engine, also faces tear and wear. At some point, you have to replace them. Knowing when to change the spark plug coil is essential. This guide will let you know when to do it as you read.

When to Change Spark Plug Coils

The spark plug coil should serve you for 100,000 miles. When this mileage is exceeded, you will start experiencing the below signs.

Power Loss

When the spark plug coils cannot transform and supply the required voltage to the spark plugs, combustion in the cylinders will not be effective. In such a situation, your truck will become sluggish and pick up slowly whenever you press the gas pedal. Power loss also results from irregular sparks within the cylinders. 

If you experience power loss and other parts, such as the fuel system, air system, and spark plugs, are working perfectly, consider checking if your spark plug coils need a replacement.

Engine Check Light

The engine of modern trucks has various sensors. The primary function of these sensors is to ensure that the entire system runs smoothly. When the spark plug coils become faulty, the sensors will take this information to the engine control module, which will light an engine check light on the dashboard.

If the engine check light shows on your dashboard, consider taking your truck for a computer check-up to read the error code. If the spark plug coils are the cause, consider replacing them.

Low Fuel Economy

A faulty spark plug coil will not supply inadequate voltage to initiate combustion but also reduce your engine’s performance. When your engine’s performance is poor, your feet will rest on the gas pedal, resulting in high fuel consumption. 

Engine Misfiring 

Your engine will misfire when you press the gas pedal once the spark plug coils become faulty. Engine misfire result from one of the cylinders not functioning effectively or dead.

Engine misfires indicate that your spark plug coils need a replacement. 

Hard Starts

For your engine to function effectively, all processes must be done promptly. For example, when igniting the engine, the fuel and air should get into the cylinder, and spark plugs should cause combustion. All these are timed processes, and if one does not happen within the required timeframe, your engine will become hard to start and sometimes even stall.


The spark plug coils, like other parts of the ignition system. Although they have a longer lifespan, they also wear out. After covering more than 100,000 miles, your spark plug coils will start becoming exhausted and faulty. When such happens, you will experience some of the above signals. When such signs start to develop, consider fixing new ones.

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