Error F12 in a Bosch washing machine

The beauty of modern washing machines is that they automatically diagnose the machine and, if problems are detected, notify the user through a code on the display or indication of the panel LEDs. In any case, you can quickly determine the cause and eliminate it. But in order to outline a plan of action, it is necessary to correctly decipher the signal. If error F12 is displayed on a Bosch machine, then the self-diagnosis system has detected a malfunction of the electric motor. Let's take a closer look at what exactly is broken and how to repair it.

F12 in Russian

To decipher the F12 error code, just look at the instructions. One glance is enough to understand that there is a problem with the electric motor.. The self-diagnosis system will not tell you more precisely; you will have to carry out an extended check.

Before removing the engine, let's outline the possible range of problems. So, the following problems lead to F12:

• worn out tips on electric brushes;
• peeled lamellas;
• broken winding.

Most often, Bosch displays “F12” due to worn electric brushes.

To more accurately determine who is to blame for the failure and what to do next, it is necessary to sequentially check each designated “point”. It is better to start with electric brushes, as it is easy to replace them with your own hands at home. If problems with lamellas or windings lead to F12, then replacing the engine and contacting a service center will not do.

Motor check progress

In any case, the reason for the appearance of F12 is “hidden” in the electric motor. Therefore, it is necessary to remove the motor from the washing machine body and check each problematic part for functionality. The procedure is as follows:

• disconnect Bosch from the power supply and sewerage;
• turn the “back” towards you;
• remove the back wall of the machine;
• we find the engine located in the lower part of the body;
• remove the drive belt from the pulley;
• loosen the central retaining bolt;
• swing the engine and pull it towards you, removing it from its seat.

Before disassembling the washing machine, you must make sure that the equipment is disconnected from the power lines!

Before you try to fix the engine, it's worth diving a little into its structure. We remember that Bosch machines use commutator motors, which are compact and powerful. The impulse from the engine is transmitted to the drum shaft through the drive belt.

Now about the “internals”. A tachogenerator is located on the motor body, which controls the degree of its rotation and transmits speed data to the control board. Next to the sensor, on both sides of the engine, there are electric brushes that smooth out the friction force. Two more integral components are the rotor and stator.

First of all, it is necessary to check the performance of the engine as a whole.

1. We establish contact between the stator and rotor windings.
2. We supply them with a voltage of 220V;
3. evaluate the result (if rotation starts, then everything is in order).

However, this verification has its own risks and difficulties. Firstly, it is impossible to test the operation of the motor in different modes. Secondly, applying voltage directly threatens a short circuit due to overheating of the engine. To reduce the likelihood of overheating, it is recommended to include a heater in the circuit, which will take over the main power from 220 V. Has the engine passed the test? This means that spot diagnostics are next - assessing the condition of brushes, lamellas and windings.

Start with brushes

It's better to start with brushes.Over time, the carbon tips wear off against the motor body, which is why the friction force is not smoothed out and sparks appear. All this leads to disrupted engine operation and the display of error F12.

Checking the integrity of the brushes is simple:

• We find brushes located on both sides - there are two of them;
• loosen the screws holding them;
• we deal with the spring mechanism and remove the brushes;
• we open each case;
• measure the length of the “coals” (minimum – 1.5 cm).

Change two electric brushes at once!

If the carbon tip is worn off, a malfunction has been detected. In this case, you need to purchase two similar brushes and replace the old ones with them.

Other engine components

Have the brushes been tested? So, let's move on to diagnosing the lamellas. These are metal plates that are glued directly to the shaft and transmit current to the winding. If peeling occurs, the transmission is disrupted and the motor is unable to operate at full power. Repair of minor detachments is limited to sharpening the surface of the engine on a lathe; in case of severe deformations, only replacing the entire assembly will help.

Damaged lamellas reveal themselves by the presence of detachments and “burrs”.

A damaged winding also causes the engine to stop. Most often, the problem is that there is a current leak, a short circuit, subsequent overheating of the motor and the thermistor triggering. The control board detects a problem and displays an error code. The guess is confirmed as follows:

• turn on the multimeter to measure Ohms;
• connect to the slats;
• We compare the result with the norm of 20-200 Ohms.

At the “finish” we check the stator with a buzzer. If you hear a squeak, the motor will have to be replaced. Repairing a damaged winding is very troublesome and expensive; it is easier and more profitable to purchase a new motor.

1 reader comment

1. 05/10/2022 at 09:01

   Azret:

   Brushes and motor are in working order. The wiring is intact. The tachometer is normal. There was brush dust on the diagram. Cleaned it. In any mode, it throws out F12 10 seconds after turning off. Entering service mode does not help. The error disappears and appears again. Bosch Maxx Advantage. Tell me, maybe I'm entering service mode incorrectly? I hold down the start button and turn the selector counterclockwise two positions.

   Answer