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. 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, as well as Volvo & Saab, Resistive Cores, favoured by British,
Japanese and American manufacturers.
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. Generally, this is caused be wear and tear, and leads
become worn out over time. Leads can also be affected more in winter months, as cold, damp conditions
increase the stress on the components whilst deterioration can be accelerated by water and salt ingress. Oil,
Coolant and Fuel Vapour can also cause oxidisation and corrosion in the connector contacts.
Symptoms of a Faulty Lead:
Check Engine Light
Reduced Fuel Efficiency
Decrease In Power
Visible Wear/Damage to Cable
SMP Europe Core Technology
This consists of copper wire with negligible resistance
with double silicone outer combined with 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 (Reactive Cable)
The 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.
The 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’s range of Original Fit Ignition Leadsets contain over 875 references making it the most
comprehensive range of OE fit sets available. Our portfolio can be purchased across all of our primary brands,
Intermotor, Lucas, High Volt and Electrospark. We are constantly monitoring the aftermarket to update our offerings
to ensure our customers remain up to date and have the sets they need for every repair.
To ensure optimum performance our lead sets are speciﬁcally tailored to each individual make and model
of vehicle. We specify the highest grade and quality materials possible, which meet or even exceed the OEM
speciﬁcation, specifying the same cable technologies as offered by the original manufacturers.
Designed to meet or exceed OE performance, our leads are manufactured at our facility in Poland. The majority
of sets use 7mm or 8mm full silicone ad copper core cable, however our range also includes 5mm cable OE
sets to cover Japanese and Korean Vehicle parc.
To maximise radio suppression, resistance to temperature, water and oil degradation and chemical attack,
all our cable is manufactured with double silicone protection. All terminals are machine crimped to ensure
strong and reliable connections over a long service life. Spark plug boots and terminal covers are moulded
from silicone to give a water tight seal.
All of our leadsets are extensively tested. This includes, “Pull Off” tests, both hot and cold temperature testing,
checks on all terminals and connections and a high voltage saline solution immersion test to check for current
Cables comprise of double silicone insulation and are manufactured using high quality Class F cable, tested to meet international ISO3808/J2031 standards.