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Today, most new vehicles have spark plugs that are resistant to corrosion and deterioration and can be expected to last over 100,000 miles. But eventually, all plugs need to be replaced, and when a spark plug stops sparking properly, it can rapidly cause further engine problems. Below are some signs your spark plugs may need to be replaced.

Your Vehicle Is No Longer Purring

The purr of an engine will start to stutter and cough when a spark plug fails. As the spark plug begins misfiring, one or more of the engine’s cylinders is no longer combusting fuel consistently. The resulting misfiring will become most notable when you’re resting in idle or starting up in the morning.

You’re Struggling to Start Your Engine

The surge of electrical power required to start an engine will be lacking with one or more plugs malfunctioning. Your engine will sound unhealthy as it struggles to cough and wobble to life. You might find it takes a few tries before you can get moving and if more than one spark plug is failing, you might not be able to start your engine at all.

You’ve Lost Acceleration

While out on the road the acceleration of your vehicle will be somewhat lackluster with a failing spark plug. This can become a little dangerous when a quick burst of acceleration is required to cross a busy intersection, overtake another car, or come out of a sharp corner.

You’re Stopping for Gas Too Often

With a faulty spark plug, fuel is no longer being ignited properly, but the fuel injector will keep pumping fuel into the combustion chamber. This leads to a drop in fuel efficiency, which will have you stopping more frequently for gas.

Your Dashboard is Alerting You

Most engine problems will be detected by your vehicle’s sensors. So, when a spark plug malfunctions, you’ll soon see the check engine light blinking on your instrument panel. It’s best not to ignore this warning light as a minor spark plug issue can soon develop into something worse if left unresolved.

Your Dealer Recommends New Plugs

Most vehicles require regular maintenance visits by a qualified technician. While inspecting your car, the technician should notice any potential problems long before the symptoms become overly apparent, including a faulty spark plug. So, if your technician suggests that you replace a spark plug soon, it’s best to do so before misfiring causes other engine problems and reduces the quality of your driving.


Be sure to consult with your dealership’s service department before starting any service work in case of warranty, buying proper parts, etc.


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