How to Change Spark Plugs: A Guide for Drivers

Changing spark plugs is a maintenance task that often sounds more complicated than it actually is. 

For many car owners, the idea of carrying this out yourself can cause hesitation. 

However, if you have the right tools and a bit of preparation, it’s a job that most people are able to carry out at home.

That said, if you’re ever in doubt, it’s always best to seek assistance from a qualified mechanic. 

A small mistake when working on an engine can lead to a larger issue. So it’s always best to err on the side of caution. 

Can I Change My Spark Plugs Myself?

In many cases, yes.

Especially if your car’s engine layout give you easy access to where the spark plugs are located.

The process doesn’t require advanced mechanical skills. However, it’s very important to practise patience and concentration.

Attention to detail is critical. It is worth noting that not all vehicles make it easy. 

Some modern engines are more compact and require the removal of other components first. 

If access seems difficult, or you're unsure at any stage, please leave the job to a professional.

How to Tell If Spark Plugs Need Replacing

There are a few signs that your spark plugs may need replacing. 

These include:

• Poor fuel economy
• Difficulty starting the car
• Rough idling
• Sluggish acceleration

You can also visually inspect a spark plug by removing one.  If the tip is heavily worn, oily, or coated in carbon, you may need to replace it. A light brown or tan deposit on the electrode is usually a sign of normal wear.

Should the Engine Be Cold When Changing Spark Plugs?

Yes - always allow the engine to cool completely before attempting to change the spark plugs.

If you are working on a hot engine, you may damage the cylinder head or lead to injury. 

Ideally, wait a few hours after driving.

Changing Spark Plugs: Step-by-Step

Here’s a general outline of what the process involves:

• Purchase the correct spark plugs for your make and model.
• Gather the tools: spark plug socket with rubber insert, ratchet, extension bar, gap gauge, and a torque wrench if available.
• Locate the spark plugs, often under coil packs or ignition leads.
• Remove the old plug carefully using the socket. 
• Check the gap on the new plug using a gap gauge. 
• Install the new plug by hand to avoid cross-threading, then tighten to the recommended torque.

Top tip: Repeat this process one plug at a time. To avoid mixing up any parts or wiring.

Is Replacing Spark Plugs an Easy Job?

Easy is subjective. It really also depends on the vehicle and your level of experience. 

The task itself is relatively straightforward, particularly on older models. Ones with simpler engine layouts. 

In newer and tighter engines, it can be time-consuming. And fiddly. If you're at all unsure, it’s best not to take risks. 

Find a qualified mechanic who can complete the job quickly and safely.

The Importance of Regular Car Servicing

While changing spark plugs can be done at home, it’s just one part of a much broader picture.

Regular car servicing helps ensure the overall health of your vehicle. From the brakes and tyres to the levels of fluid and the filters.

A professional service often includes testing a spark plug, inspecting electrical systems, and checking for early signs of wear or damage elsewhere. 

So even if you’re comfortable with basic maintenance, don’t skip your annual or mileage-based service.