Spark Plugs in Watsonville, CA A spark plug is a device for delivering an electric spark into the combustion chamber of your engine. It ignites the compressed mixture of fuel and air causing the pistons to move up and down. And the power from the pistons is what ultimately keeps your car moving. We recommend getting your spark plugs checked every 30,000 miles but if you are having problems starting your car, or it makes noises while idling, chances are that your spark plugs are misfiring. Replacing your spark plugs is part of routine maintenance, but if left unchecked, engine performance and fuel efficiency will suffer If ignored long enough, damaged spark plugs can extremely difficult or even impossible to remove when the time comes. Without a spark, your car won’t start, might stall and could leave you stranded And from an environmental point of view, fully functioning spark plugs will not only save gas, but reduce air pollution.