All about U6
Design of NGK Coil Systems
U6 coils can consist of multiple single or double spark coils, which are combined in one system.
U6004, used by PSA. It consists of two "wasted spark" coils, supplying four cylinders.
For details of this technology, refer to the description of the U4 coils.
U6019, used by GM. Four individual coils in one system.
For details of this technology, refer to the description of the U5 coils.