Bosch Washer Error Code F:43

The F:43 error code on a Bosch washer indicates that the drum motor is failing to rotate. The control board monitors drum rotation through a speed sensor (also called a tachometer), and when it detects no rotational signal during a cycle, it triggers this fault. Because the code is flagged as a remanent error, it is stored in memory even after power is removed, meaning a deliberate reset through test mode is required to clear it rather than simply unplugging the machine.

There are four primary causes the control system associates with this fault: a failed or disconnected speed sensor, a drum physically blocked by laundry (such as an item jammed between the drum and the tub), a mechanically seized motor, or a failed Triac on the control board that prevents the motor from receiving the proper drive signal. The speed sensor communicates drum rotation data back to the control board, so a broken or open-circuit sensor will cause the board to conclude the drum is not moving even if the motor is functioning. A faulty Triac, on the other hand, means the motor never receives the signal to start at all.

Diagnosis begins by entering test mode to reset the stored fault, then checking the drum manually for obstructions. From there, the speed sensor and its wiring harness should be inspected for continuity and secure connections at both the sensor and the control board. If the sensor checks out, the motor itself should be evaluated for signs of seizure or winding failure, and the control board examined for Triac damage, which may appear as visible burn marks or scorching near the motor drive circuit.