How to Tell If a Spark Plug Is Bad in My Nissan

June 24, 2021

Spark plugs are a crucial component of your cars ignition system. Without them, the engine wouldn't run. Spark plugs ignite the air-fuel mixture in your engines combustion chamber, which drives the pistons and cranks your engine.

A good spark plug will keep the engine running efficiently, whereas a faulty spark plug can cause a range of problems in your Nissans performance ‐ or may prevent your car from starting at all. How can you tell if a spark plug is bad? Look for these common bad spark plug symptoms to determine if you need to replace any worn-out spark plugs on your Nissan.

Bad Spark Plug Symptoms

Like most vehicle parts, spark plugs eventually need replacing. The electrodes on each spark plug slowly wear down until they cant produce a spark at all. While this wear is normal and expected with a properly maintained engine, other factors such as overheating, oil contamination, and carbon buildup can cause spark plugs to fail prematurely.

Replace the spark plugs in your Nissan approximately every 100,000 miles. The exact interval will depend on the type of spark plugs in your vehicle, so check your owners manual for model-specific recommendations. If you're unsure of the last time your spark plugs were replaced, these common signs of worn-out spark plugs may be good indicators that its time to replace yours.

Slow Acceleration

If you notice your Nissan feels sluggish and is noticeably slower when accelerating, you may be dealing with worn-out spark plugs. As the conductive material in each spark plug degrades over time, its sparks will lose effectiveness. The electric arc from a spark plug must be hot enough to ignite the air-fuel mixture in the engine, but a bad spark may not properly ignite the mixture. This improper combustion leads to an underpowered engine. Since spark plugs typically wear down at the same rate, the collective power reduction to your engine often results in a noticeable lack of acceleration while driving.

Poor Fuel Economy

For a spark plug to work properly, the gap between electrodes must be just right. When that gap is either too small or too large, the spark wont properly ignite the air-fuel mixture in the combustion chamber. Inefficient combustion means your engine must work harder to produce power when you press on the gas pedal, resulting in greater fuel consumption. If you notice a drop in your vehicles usual mileage per gallon, faulty spark plugs may be to blame.

Engine Misfiring

Whether its a faulty ignition coil, fuel injector, or spark plug, an engine that's misfiring is usually the result of a problem with the ignition system. Similar to previous symptoms, if your engine is constantly misfiring, it could be that a damaged spark plug or spark plug wire is not properly igniting the air-fuel mixture. Engine misfires are characterized by irregular sputtering and stumbling from the engine accompanied by a popping sound and overall loss of power.

Rough Idling & Vibrations

A rough idle is often the result of your engine misfiring, possibly from failing spark plugs. An engine that's not firing properly on all cylinders will be off balance and shake excessively. Vibrations from engine misfires will be more noticeable when idling.

Trouble Starting Your Car

If your spark plugs are worn down, you may experience difficulty starting your car. A spark that's too weak wont ignite the fuel quickly enough, meaning you may have to crank the engine longer to create combustion. If your spark plugs have stopped producing a spark altogether, you wont be able to start your car at all.

Check Engine Light Is Flashing

Bad spark plugs are among the many potential causes for your check engine light to appear. In this case, the check engine light typically comes on as a result of engine misfires caused by faulty spark plugs. If your check engine light is flashing, it could mean the misfires are potentially causing severe damage to the engine, catalytic converter, and other important components.

Can You Replace Your Own Spark Plugs?

It is not recommended to replace your own spark plugs at home. Spark plugs are difficult to access, and there may even be more than one spark plug per engine cylinder. Without the proper knowledge and professional expertise, replacing your own spark plugs could cause serious damage to your engine. Additionally, it may be easy to strip the small threads on the spark plug when installing the new ones, leading to a malfunctioning spark plug and major engine problems down the road.

When having your spark plugs replaced, its best to use manufacturer-recommended spark plug replacement parts ‐ your Nissans original spark plugs were designed to work with your specific model. Even slight irregularities could lead to fuel efficiency differences, engine trouble, and potential repairs down the road.

Need new spark plugs? Get replacement spark plugs designed for your Nissan model and year! Shop online for Nissan spark plugs, then turn to your nearest authorized service center for professional installation.