NGK U5051 / 48179 Ignition Coil Genuine NGK Component Essentially the operating principle is the same for all types of ignition coils whether the classic can-type coil, or in a coil rail system. The device contains two copper wire windings and a laminated iron core. The copper wires are insulated to prevent short circuits. The battery current fed through the primary winding produces a magnetic field whose strength is further increased by the iron core. When this circuit is opened, the magnetic field collapses, inducing a high voltage pulse in the secondary coil. U5 Type Ignition Coil No ignition cables are required The NGK ignition coil of the Type U5 is a pencil coil with single spark technology. One such ignition coil is attached at each cylinder. Alternatively please use the cross reference table above.