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Up to 25% Off Online Orders of Select Parts & Accessories. Enter Promo Code MMJ25 in Cart.

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Receive Up To 25% Off Your Online Purchase Of Select Parts and Accessories Instantly

When items are added to the cart, the discount will automatically deduct off the price of the qualifying items. Offers not valid in combination with any other discounts, promotions or items already on sale. Not valid on gift cards, special orders, installation, commercial or fleet purchases. Those products that are included in these offers will be displayed in product search results and product detail pages. Excludes select products, items already on sale and MAP priced brands & items. For full category inclusions and disclaimers, See Details Here. Valid online until 11:59 PM EST on 5/31/18.

Additional Promotions Not Included in the above:

Receive 10% Off Select Wagner branded brake parts with your online purchase. Use promotional code: WAGNER10.

Receive 10% Off Select Champion branded products with your online purchase. Use promotional code: CHAMP10.

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Spark Plugs



Spark Plugs

Most vehicles on the road today are equipped with spark plugs. Changing your vehicle's spark plugs at the appropriate mileage intervals is an important part of keeping your vehicle operating efficiently. Most spark plugs are relatively inexpensive and can be properly installed by novice to intermediate level DIY'ers.

What is a Spark Plug and how does it work

What is it?

  • A spark plug is a device used in a gas fueled internal combustion engine. It is threaded into the cylinder head and its tip protrudes into the combustion chamber.
  • Its purpose is to create a spark to ignite the air/fuel mixture that keeps the engine running.

How Does it Work?

  • A spark plug channels the energy from your vehicle's ignition coil across an air gap in the combustion chamber.
  • This spark ignites the compressed fuel/air mixture within each cylinder and the resulting combustion initiates the engines power stroke.

How is it Made?

  • A spark plug is made up of a center electrode, ground electrode, resistor (in most cases) and a terminal stud that are assembled inside a ceramic insulator.
  • This insulator assembly is then inserted into a steel shell that is designed to thread into the cylinder head.

Why Does it Fail?

  • Electrode Erosion.
  • Fouling.
  • Resistor Burnout.
  • Material Failure.

What are the Symptoms of Failure?

  • Check Engine Light.
  • Misfire.
  • Hesitation.
  • Hard Starting.

What are the Implications of Failure?

  • Poor Fuel Economy.
  • Poor Engine Performance.
  • Dead Cylinder(s).
  • Engine Damage.

How Difficult is the Install?

Difficulty Rating:


  • Installation difficulty depends on vehicle and engine size/position.

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