The automatic transmissions are equipped with shift solenoids, which are controlled by the Powertrain Control Module (PCM). These contribute to the change of transmission fluid between the various hydraulic circuits. Their purpose is to get the most efficient gear changes. It should be noted that regardless of the number of transmission ratios, there is a solenoid for each ratio.
The setting of DTC code P0755 OBDII means that the PCM found a malfunction in the control circuit of gear shift solenoid B, indicating that the solenoid cannot control gear shifts efficiently.