Modern vehicles have eliminated the use of ignition components such as distributor, cap, rotor, and even spark plug wires. They now use only a coil pack that is located directly on top of the spark plug. The purpose of using the coil pack is to convert the low voltage of the primary circuit to high secondary voltage, which is necessary to trigger the plugs.
When the diagnostic code P0355 OBDII is set, it is due to a problem that has been observed in the ignition coil circuit. The last digit of the code refers to the coil where the fault starts. In this case, it indicates a problem in the circuit of coil number 5.