Changing Spark Plugs: Simple Steps to Keep Your Engine Happy

Feel like your ride is coughing or the fuel gauge is acting up? Most of the time it’s the spark plugs. These tiny metal pieces fire the fuel‑air mix in each cylinder. When they wear out, you get rough idling, loss of power, and higher fuel bills. The good news? Swapping them out is one of the easiest DIY jobs you can tackle at home.

Why spark plugs matter

Every time you start the car, the ignition coil sends a high‑voltage spark to the plug. A fresh plug creates a clean, strong spark that burns the fuel efficiently. Worn plugs have fouled electrodes, larger gaps, or cracked insulators. The result is incomplete combustion, which feels like a sluggish engine and can even damage other components over time. Replacing plugs restores proper ignition, improves fuel economy by up to 10%, and reduces emissions.

Step‑by‑step guide to changing them

1. Gather the right tools. You’ll need a spark‑plug socket (usually 5/8" or 13/16"), a ratchet, a torque wrench, and maybe a gap gauge if your new plugs aren’t pre‑gapped. A small brush helps clean debris around the plug wells.

2. Check the service interval. Most manufacturers suggest changing plugs every 30,000–50,000 miles for copper plugs, and up to 100,000 miles for iridium or platinum types. Your owner’s manual or the sticker on the old plug will give you the exact gap and heat range.

3. Locate the plugs. Open the hood and find the ignition coil or spark‑plug wires on top of the engine. In modern cars they’re often under a plastic cover. Take a photo of the wiring order before you pull anything off.

4. Remove the old plug. Use the socket and gently turn counter‑clockwise. If it’s stuck, apply a little penetrating oil and wait a few minutes. Pull the plug straight out to avoid bending the threads.

5. Inspect and prep. Look at the old plug’s electrode wear and any carbon build‑up. Clean the plug well with the brush to remove dirt that could fall into the cylinder. Compare the new plug’s gap with the spec – adjust with the gap gauge if needed.

6. Install the new plug. Screw it in by hand until the threads bite, then use the torque wrench to tighten to the manufacturer’s torque (usually 13–20 ft‑lb). Over‑tightening can strip the threads; under‑tightening can cause heat loss.

7. Re‑connect the coil or wire. Follow the photo you took earlier and push the connector back onto the plug until it clicks. Double‑check that everything is snug.

8. Test the engine. Start the car and listen. The idle should be smooth, and acceleration should feel snappier. If you notice misfires, double‑check the plug gap and wiring order.

Changing spark plugs yourself can save you up to £50 in labour and give you a better feel for your vehicle. If you ever feel unsure, a quick call to a local garage like Northwich Tyres Centre can confirm you’ve done it right – they also stock premium plugs and can fit them for a modest fee.

Bottom line: fresh spark plugs are a cheap upgrade that pays for itself in fuel savings, smoother driving, and fewer engine headaches. Keep an eye on performance signs, check your mileage, and change them before the next big service. Your engine will thank you.