P0750 is the generic OBD-II code for Shift Solenoid “A” Malfunction. In Toyota factory manuals, this is described as shift solenoid valve SL1 / S1 malfunction, and the usual fault tree includes a stuck-open or stuck-closed solenoid, a blocked or sticking valve body passage, ECM issues, torque-converter-clutch-related faults, or internal automatic transaxle problems.

