Ignition Lead (Spark Plug Wire)
Ignition leads carry high voltage from the coil or distributor to the spark plugs.
What is Ignition Lead (Spark Plug Wire)?
They are insulated to prevent leakage. Coil-on-plug systems have no leads. Leads age with heat. Measuring lead resistance with a multimeter and comparing it with the specification shows internal breaks. Spraying a fine mist of water near the leads with the engine running in the dark can reveal sparks jumping to ground, but take care around high voltage.
How it works
The lead conducts the high voltage pulse to the plug.
Why it matters for your car
Cracked leads can cause misfires in damp weather. Replace leads as a set.
Other terms
- Bore And Stroke
- Brake Fluid
- Car Segments (A To F)
- Car Sharing
- Cargo Barrier (Dog Guard)
- City Car
- Cold Air Intake
- Diesel Particulate Filter (DPF)
- Engine Code
- Engine Stalling
- Fuse
- Ignition Switch
- Piston Pin (Wrist Pin, Gudgeon Pin)
- Piston Slap
- READY Indicator (EV And Hybrid)
- Starting Handle (Crank Handle)
- Structural Adhesive (Body Bonding)
- Usable Battery Capacity (Net Capacity)
- W Engine (W12, W16)
- Wheelbase