Symptoms of Failure of Spark plug and How to Replace it

by Jonathan Cogley

Get to know about Spark plug
The main function of the spark plug is to ignite air-fuel mixture in the combustion chamber/ cylinder. Spark plugs are mostly used in petrol engines. The electric spark is produced by the electronic control unit. The electric spark ignites the air-fuel mixture. The ignition coil sends high voltage electric spark to the distributor. The distributor sends High voltage electric spark plug according as required. Spark plug is an important component in the ignition system of a car/ vehicle.

Spark plug location
The spark plug is an essential component in the fuel ignition system. It is located above/top of the cylinder in the engine. A series of spark plugs are connected to the cylinders. Each cylinder consists of one spark plug. The number of spark plugs in the engine depends upon the number of cylinders.

Symptoms of failure of spark plug
Some symptoms of failure of spark plug are:

  • Poor acceleration
  • High fuel consumption
  • Engine surging

Poor acceleration

  • One of the common signs a faulty spark plug is poor acceleration.
  • When you accelerate your car, you will come across the issue of not picking up speed even you accelerate this is due to the failure of spark plug.

High fuel consumption

  • If spark plug is in bad condition, your car consumes more fuel than normal.
  • Due to failure of spark plug, incomplete combustion takes place and even misfiring of ignition system at the exhaust occurs.

Engine surging

  • If the spark plug is in bad condition, your car takes more air than in normal combustion process.
  • This issue can cause jerking of car and even continually starts and stops, it is also known as engine hesitation.

How to replace spark plug

  • First, switch off the engine of your car and locate the spark plug.
  • If you are not aware of where the spark plug is located, refer to the user manual.
  • The spark plug is located at the top of the cylinder/engine.
  • Disconnect the wires that are mounted on the spark plug.
  • Remove the spark plug wire carefully and gently to avoid breaking of spark plug wires.
  • Now remove the spark plug from its position.
  • Check spark plug you will find white lime built up around the electrodes of the spark plugs, cracks on spark plug.
  • Take a new spark plug, before installing clean surrounding where new spark plug as to be installed.
  • Now install a new spark plug and tighten the screws.
  • After fastening the spark plug, put anti-seize lubricant around the threads of the spark plug to prevent reaction between dissimilar metals.


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