Once you note error code F21, unplug the device from the mains immediately as power connection increases the risk of electric shocks. Afterward, call an expert or self-search the solution.
Interpretation and description of the F21 code of the Bosch washing machine
Other than displaying the error code, some washer models only blink on the control panel. However, a blinking indicator is a sign of dozens of other errors, and therefore by the panel flashing, it cannot be concluded to be F21. To detect the presence of the error, you can the special table of error codes.
The image below shows how the error code F21 can be detected even if it’s not displayed on the screen. The following stages happen: The washer freezes and stops responding to button presses. Then, it turns the program selector knob. Three light bulbs begin to flash or blink at the same time (1000 revolutions, 800 revolutions, and rinsing or 800/600 revolutions and rinsing on the older models).
Defining the exact cause of the error is quite complicated. According to experts, the device fails to rotate the drum despite the several attempts by the washer to start the rotations, and due to the failure, error code F21 is displayed.
Why the washing machine cannot start the rotation of the drum?
- The Tacho sensor is defective. The module doesn’t get information about the engine speed. So, it stops the Bosch washing machine and gives the F21 error code.
- The engine may be out of order. If the motor is broken, it will be not able to rotate. Accordingly, the module makes several attempts to start the engine.
- A chain that powers the motor or a Hall sensor (tacho sensor) is damaged. In this case, the sensor and the motor are in order, but their feeding wiring is broken or rather oxidized.
- Foreign object. If clogs and other unfeasible materials enter into the tank during washing, this may hinder the drum.
- Voltage drop in the mains.
To repair the error code, specific actions have to be taken. If the Tacho sensor is defective or the engine is out of order, they may need replacement. Additionally, the foreign materials which lead to clogging or blockages should be cleaned with running water. Also, ensure that the voltage is in the right range. To do this, test it using a multimeter and solder any leak in the wires and connectors or replace them as appropriate.