All about U2
The U2 coding describes a block coil with multiple high voltage outputs. A coil like this supplies multiple spark plugs at once. Depending on the vehicle, one or more of these ignition coils would be required. The number of ignition cables corresponds to the number of spark plugs.
In a block coil, multiple ignition coils are combined and produce multiple spark plugs via ignition cables. Most block coils do this using dual spark (also called "wasted spark") technology.
Depending on the manufacturer's requirements, one block coil can therefore supply at least two spark plugs. A block coil with four high voltage outputs can supply an entire 4-cylinder engine.
Block coils work with static distribution. They are triggered with the help of the ignition module, in order to control the precise timing of the ignition spark.
Depending on the vehicle, the ignition module is either part of the engine control system or already integrated into the block coil.
A block coil can generate ignition voltages of up to 36,000 volts.