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4.8 • based on 11 reviews of 11 businesses

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Average rating for Vehicle misfiring inspection


4.8 • based on 11 reviews of 11 businesses

Vehicle Misfiring Inspection

How Much Does a Vehicle Misfiring Inspection Cost?


One of the most common causes for an engine misfire is excessively worn or failed spark plugs. The spark plugs are one of the most important parts when it comes to igniting the fuel and air mixture inside the engine, and if they are not working to their full capacity, will cause the engine to misfire and vibrate excessively as the combustion process is not carried out efficiently.

Not only will this cause increased fuel consumption, but may also cause damage to sensitive components inside the engine and exhaust.

Spark plugs do wear out over time, and most manufacturers recommend spark plugs to be replaced at certain intervals to maintain engine performance and efficiency.

Modern petrol engines usually have one spark plug for each cylinder, although there are some engines that have two spark plugs per cylinder.

How Do Spark Plugs Work?

Spark plugs are commonly made of copper, although some modern vehicles use spark plugs made of platinum or iridium for longer durability.

This allows them to effectively transmit the electrical power supplied by the ignition system to ignite the air/fuel mixture inside the cylinders of the engine.

They are fired thousands of times per minute with precise accuracy by an electrical current that is controlled by the engine control unit (ECU).

Common Signs Your Spark Plugs May Require Replacing

  • Decreasing fuel economy
  • Increased engine vibration or engine misfire
  • Poor engine performance
  • Check Engine Light is on

How are the Spark Plugs Inspected?

  • The vehicles computer system is scanned for any Diagnostic Trouble Codes (DTC)
  • The bonnet is opened and the surface around the ignition system is cleaned of dirt and debris
  • The inlet manifold is removed (If required)
  • The ignition leads or coil packs are disconnected, and the spark plugs removed
  • The threads in the cylinder head are inspected for damage
  • The old spark plugs are inspected for any signs of damage
  • If requested, a compression test may be carried out (at an additional charge)
  • The mechanic will provide a report and quote for any work required

How Important is a Spark Plug Inspection?

Operating a vehicle that has excessively worn spark plugs can cause other damage, especially if the vehicle is misfiring.

This allows un-burned fuel to enter the exhaust and may cause expensive damage to the catalytic converter, as well as expensive internal engine damage.

If you notice that your vehicle is misfiring, it is best to have your vehicle inspected immediately, to prevent any damage occurring and return your vehicle to smooth running operation.

If you've read this far, you obviously care about your car. A lot. So next time you need a service, repair or inspection, visit AutoGuru. We let you search and book from over 1,600 qualified mechanics, who eat car troubles for breakfast.