Spark Plugs Buying Guide
Last updated: 24 April 2026
Spark plugs ignite the air-fuel mixture in petrol engines. Worn plugs cause misfires, rough idling, poor fuel economy, and increased emissions. Modern iridium and platinum plugs can last 60,000+ miles but should be checked at every major service.
Spark plug types and materials
Choose the right plug for your engine's requirements.
- Copper/nickel: cheapest, 20,000-30,000 mile life, adequate for older engines
- Platinum: longer life (60,000 miles), better resistance to electrode erosion
- Iridium: finest tip, longest life (80,000-100,000 miles), best for modern engines
- Double platinum/iridium: premium longevity for waste-spark ignition systems
- Always match the heat range and thread size specified by the manufacturer
Category page
- Browse matching parts
Copper, platinum, or iridium? Understand heat ranges, gap settings, and when to replace spark plugs.
Related guides
- Glow Plug Buying Guide
Diesel cold-start problems — glow plug failure symptoms, removal tips for seized plugs, and replacement advice.
- Ignition Coils Guide
Misfires and rough idle? How to identify a faulty coil with an OBD scanner and decide on replacement.
- Ignition Switch Buying Guide
No-start faults, intermittent power loss, and key won't turn — how to diagnose and replace a faulty ignition switch.
Frequently Asked Questions
How often should spark plugs be replaced?
Copper plugs every 20,000-30,000 miles, platinum every 60,000 miles, iridium every 80,000-100,000 miles. Check your vehicle's service manual.
What are the symptoms of bad spark plugs?
Rough idle, engine misfires, poor acceleration, increased fuel consumption, difficulty starting, and illuminated check engine light.
Can I mix different spark plug brands?
It's best to use the same brand and type across all cylinders. Mixing can cause uneven combustion. Always replace as a complete set.
How much does spark plug replacement cost?
The price of spark plugs depends on your exact vehicle and the brand you choose. Enter your registration above to see parts confirmed to fit, then compare prices from the brands we stock on this page. Free UK delivery on orders over £99.
Related Guides
Diesel cold-start problems — glow plug failure symptoms, removal tips for seized plugs, and replacement advice.
Ignition Coils GuideMisfires and rough idle? How to identify a faulty coil with an OBD scanner and decide on replacement.
Ignition Switch Buying GuideNo-start faults, intermittent power loss, and key won't turn — how to diagnose and replace a faulty ignition switch.
Ready to find the right part?
Browse spare parts