SMP Europe continues to drive the market from the front with its range of OE Fit Ignition Leads, now available in its Intermotor, Lucas, Lemark, High Volt and Electrospark brands.

What is an ignition lead?

Sometimes known as high-tension (HT) leads or spark plug wires, ignition leads carry an electrical current from the ignition coil into the spark plugs, ultimately, lighting the fuel and air within the combustion chamber of the engine.

Comprised of conductive material surrounded by a silicone jacket for protection, ignition leads sit in close proximity to the engine and must therefore be able to withstand dramatic temperature changes, caustic chemicals and high physical forces.

Why do ignition leads fail?

Ignition leads are made from durable, low resistance materials, and tested to withstand the harsh environment that they operate. Conductive materials in the leads will deteriorate, which in turn reduces the power able to reach the engine, compromising the ignition process.

This is generally caused be wear and tear over time. Leads can also be affected more in winter months, as cold, damp conditions increase the stress on the components, while deterioration can be accelerated by water and salt. Oil, coolant and fuel vapour can also cause oxidisation and corrosion in the connector contacts.

The main symptoms of a faulty lead include: an engine light appearing, reduced fuel efficiency, decrease in power, visible wear and tear to cable and misfiring.

SMP Europe core technology

Lead cores can vary depending on vehicle manufacturer and the age of the vehicle. The three technologies used are: Copper cores, used mainly by German manufacturers; wire wound (Reactive), commonly found in French vehicles, Volvo and Saab; and finally resistive cores, favoured by British, Japanese and American manufacturers.

Copper core consists of copper wire with negligible resistance with double silicone outer combined and boots, having an inbuilt resistance to generate the required suppression. The complex nature of copper core componentry makes this technology more expensive than the other technology types available. This type of cable is predominantly used by German manufacturers.

Wire wound core cable is made up of a carbon-coated fibreglass core enclosed in stainless steel windings and double silicone outer jacket. Engineered to meet or exceed SAE specifications for radio frequency interference, suppression comes from a magnetic field created when current crosses the steel winding. This type of cable is mainly used by French and Japanese vehicle manufacturers, as well as Saab and Volvo.

Resistive core cable contains a graphite coated fibreglass core, which is surrounded by a conductive latex coating and double silicone outer. This is the simplest and most robust of the cables used and works by providing resistance along the length of the cable. This type of technology is typically used by American, British and Asian vehicle manufacturers.

SMP Europe OE Fit Leadsets

SMP Europe constantly monitors the aftermarket to update its offerings to ensure customers remain up to date and have the sets they need for every repair. Its range of Original Fit Ignition Leadsets contain over 875 references, making it the most comprehensive range of OE fit sets available.

SMP Europe’s portfolio can be purchased across all of its primary brands; Intermotor, Lucas, Lemark, High Volt and Electrospark.

To ensure optimum performance, SMP Europe’s lead sets are specifically tailored to each individual make and model of vehicle. Specifying the highest grade and quality materials possible, which meet or even exceed the OEM specification.

Designed to meet or exceed OE performance, SMP Europe’s leads are manufactured at its facility in Poland. The majority of sets use 7mm or 8mm full silicone ad copper core cable. However, its range also includes 5mm cable OE sets to cover Japanese and Korean vehicle parc.

SMP Europe’s cable is manufactured with double silicone protection to maximise radio suppression, resistance to temperature, water and oil degradation and chemical attack.

All terminals are machine crimped to ensure strong and reliable connections over a long service life. And spark plug boots and terminal covers are moulded from silicone to give a watertight seal.

All leadsets are extensively tested, including: ‘pull off’ tests, both hot and cold temperature testing, checks on all terminal connections and a high voltage saline solution immersion test to check for current seepage.

Cables comprise of double silicone insulation and are manufactured using high quality Class F cable, tested to meet international ISO3808/J2031 standards.

For more information on SMP Europe’s range of Ignition Leadsets please visit