How to replace a spark plug in your car

If your car won’t start, one of the reasons could be that you need to replace your spark plug.  Here we will show you how to replace a spark plug in your car.

How do I replace a spark plug in my car?

  • Replace spark plugs every 20,000kms
  • Only buy good quality spare-parts
  • Always refer to your owner’s manual
  • Changing spark plugs is relatively easy
  • All you need are the right tools and know-how


Spark plugs are what power your vehicle – they channel electrical current from your vehicle’s ignition to ignite the fuel.

Spark plugs need replacing for wear and tear and it is a relatively simple procedure if you have the right tools and know-how.

What tools do I require? – How to replace a spark plug

How To Replace A Spark PlugA ratchet socket drive wrench

An extension bar

A spark plug socket which is normally included in ratchet socket sets

A spark gap gauge or feeler gauge

Before you even begin

Before you even start to think about changing a spark plug make sure to refer to your owner’s manual that will illustrate the positioning of the plugs in the engine housing.

The know-how – How to replace a spark plug

  1. When you open the bonnet of the vehicle you will see between four to eight wires (depending on the make and model of the vehicle) leading to the engine compartment. The spark plugs are attached to the end of those wires, secured by covers.
  2. Remove the spark plug by gripping the wire at the bottom and wiggling it gently to reveal the spark plug.
  3. Now, fit the socket wrench with the extension bar and, using the ratchet, slowly remove the spark plug from its housing.
  4. Check the gap to ascertain whether or not the spark plug needs replacing. Most spark plugs are pre-set according to the make and model of the vehicle but the gap should normally be between .028 inch to .060 inch and it is always wise to double-check.
  5. You will also need to replace the spark plug if the contacts are burnt out. You can tell if this is needed by a white, limey or sooty build-up around the electrodes. Also, check for any signs of burn-marks.
  6. Remove spark plugs one at a time. Never lose track of the order of the spark plugs because they fire the engine in a specific order sequence.


Recommendations on how to replace a spark plug

Follow these recommendations for a hassle-free spark plug change.

  1. Never change spark plugs when the engine is warm.
  2. When changing spark plugs, also inspect the leads and if they show any signs of cracking or other damage replace them immediately.
  3. If you remove more than one spark plug at a time, remember to track their leads by marking them separately. Masking tape is good for this exercise.
  4. Spark plugs should be replaced every 20,000kms unless otherwise indicated in your owner’s manual.
  5. Always buy good quality or genuine spark plugs. Spending a few Rand more will give you that extra peace-of-mind.
  6. Sparks plugs and all other necessary tools can be purchased at your local auto-parts dealer.


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All info was correct at time of publishing June 21, 2018