NGK Ignition Coil For Opel Tigra Petrol Convertible 06/2004 To 12/2010 U6003. NGK U6003 / 48011 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 ...