3 Must-Know Facts About Automotive Spark Plugs

Spark plugs, which are located in a vehicle's combustion chamber, are critical components of a car engine. Over time, you need to replace spark plugs because they endure some beating, including electrical degradation, intense pressure, chemical attack from fuel combustion and temperature fluctuations. With the right tools and knowledge of a car engine, changing spark plugs is an easy task. However, it is recommended to let a qualified car mechanic inspect your spark plugs and replace them at the right time. Here are some facts for first-time car owners to know about spark plugs.

Service Life

Most modern cars come fitted with iridium spark plugs straight from an assembly line. Such plugs have a longer service life of at least 50,000 miles (approximately 80,000 kilometres). On the other hand, standard copper spark plugs can last between 20,000-40,000 miles when appropriately installed. However, it is worth noting that iridium or copper spark plugs might have a shorter lifespan due to a host of factors, such as poor installation, carbon fouling, and chemical damage. If you require something that will last beyond 100,000 miles, then it is advisable to buy platinum spark plugs.

Time for Replacement

After spark plugs have served you for years or a certain mileage, depending on the make and model of your vehicle, you will be required to replace them. Over time, as sparks move between electrodes, the metallic part is eroded, causing an increase in the gap between electrodes. As the gap grows, sparks eventually fail to bridge the space. You are likely to experience overconsumption of fuel, engine misfires, and weakened acceleration. Also, the "check engine" sign might be activated on a dashboard. Although these signs are not ironclad, they can point you in the right direction as far as spark plug replacement is concerned. Conversely, you can take your vehicle to a mechanic for spark plug inspection. Remember that early detection of spark plug problems can prevent costly engine problems.


When installing new spark plugs, you should apply enough torque to enable adequate heat transfer. Under-torquing spark plugs can cause less contact with an engine's cylinder head. Consequently, the plugs will not transfer heat accordingly, which leads to an increase of temperature in a combustion chamber. Excess heat causes an engine to pre-ignite or detonate. Notably, detonation and pre-ignition are some of the leading causes of engine damage. In contrast, over-torquing a spark plug can damage its threads or break the metal shell because of increased stress. When you over-tighten a spark plug, you can cause its internal gas seal to malfunction, which renders a spark plug unusable. Therefore, always use the right tool, such as a torque wrench, to tighten spark plugs.

Reach out to a car service if you think your spark plug needs to be replaced.