Error F21 in a Bosch washing machine
If your Bosch washing machine once generated an error code F21, and the plugs or machine were not knocked out, you are still very lucky. If such an error occurs, technicians strongly recommend immediately disconnecting the Bosch washing machine from the power supply, and only then calling a specialist. Searching for a solution to a problem on your own, especially with powered equipment, can result in electric shock. However, we will not scare you ahead of time; we will deal with this error in order.
Interpretation and description of the code
Error F21 in a Bosch washing machine can appear not only in the form of an alphanumeric code, but also in the form of a set of flashing control panel indicators. This is explained by the fact that some models of Bosch washing machines do not have a display and, accordingly, there is simply nowhere to display the F21 code.
Dozens of errors can be recognized by a system of flashing indicators. The craftsmen do this offhand, since they have extensive experience working with such machines. The user can also do this using a special table of error codes.
In the picture below we showed how the F21 code is displayed on Bosch without a display. The following happens: the washing machine freezes, stops responding to button presses and turns of the program selector knob, and three lights begin to light or flash simultaneously - 1000 revolutions, 800 revolutions and rinse. If you have an older model of washing machine that spins at a maximum of eight hundred revolutions, then the 800 revolutions, 600 revolutions and rinse indicators will light up.
The decoding of this error is very simple, but this does not mean that it is also easy to find the reasons for its occurrence. Error code F21 is interpreted by technicians as: it is not possible to rotate the drum of a Bosch washing machine. In fact, the machine tries to start rotation several times and if it fails, code F21 will appear on the control panel. Why did this code appear, why was the washing machine unable to start rotating the drum?
- The tachometer is faulty. Information about engine speed is not transmitted to the control module, which means it simply stops the operation of the Bosch machine and displays code F
- The engine has failed. If the motor is broken, then it is not capable of rotating the drum, so the module, after several attempts to start the engine, displays the indicated error.
- Open circuit that powers the motor or Hall sensor (tacho sensor). In this case, the sensor and motor are working, but the wiring supplying them is broken, or the contacts have oxidized.
- The cause of error F12 may be a foreign object that accidentally fell into the tank during washing and jammed the drum.
- The reason for the appearance of code F12 can also be a voltage drop in the electrical network.
Hall sensor is faulty
Having deciphered the F12 error and determined the reasons for its occurrence, we ask ourselves new questions: how to eliminate the malfunction that generated the code, and most importantly, how to quickly detect it, preferably, without the involvement of a technician. There are no universal recipes for troubleshooting; you need to start checking all the above reasons in a manner convenient for you until you come across a breakdown.
Let's start with the Hall sensor. Please understand correctly, we chose this verification procedure not for practical reasons, but in order to better structure the article. You will most likely choose a different order - from simple to complex, and this will be quite reasonable.For example, first check whether the rotation of the drum is obstructed by foreign objects, then check the voltage in the electrical network and only then climb into the housing in order to test the motor and Hall sensor.
However, let's not go off topic. In the first few steps, we were faced with a difficulty associated with gaining access to the tachometer and motor of the Bosch washing machine. How to get to these details?
- We slowly turn off the washing machine and take it out somewhere where there is more free space.
- We dismantle the back wall of the washing machine body, after which we remove the drive belt, which will probably interfere with us.
- We take pictures with our phone of the location of the wires and fasteners so as not to confuse anything later, and remove the engine.
To quickly remove the motor from a Bosch washing machine, you must first disconnect the chips with wires from the motor, then unscrew the retaining bolts, then press on the body of the part so that it moves a little forward and pull it down.
The tachometer is located directly on the engine housing, so we need to remove it and carefully inspect it. There may be traces of oxide and grease on the inner surface of the tachometer ring; they need to be removed. Next, we take a device called a multimeter and check the Hall sensor; if it turns out that the tachogenerator is burnt out, it will need to be replaced immediately.
Engine problems
The Bosch Maxx 5 washing machine and other Russian-assembled models are often “noted” in service centers with serious problems with the engine. The simplest thing that can happen to it is a problem with the brushes. Brushes on commutator motors are worn out quite often and replacing them is a common thing for a technician. An amateur will have to tinker a little with brushes, but this repair is still classified as simple, so you can do it yourself, especially if you read our publication How to change brushes on a Bosch washing machine?
It will be much worse if the motor leaks current to the housing, or if several turns of its winding are broken. In this case, 99% of the time the entire motor needs to be replaced. At least it will be cheaper than rebuilding the old engine. But let's not talk about sad things, first you need to check everything. We set up our device (multimeter) and check the housing for leaks. If there is no leakage, then we check each turn of the winding, trying to detect a breakdown. This is painstaking work, but it will allow you to accurately determine whether the engine is working or not.
Other malfunctions
Before we move on to other malfunctions that generate error F21, let's figure out how to reset the error on a Bosch brand washing machine. You may ask, why reset the error at all, because if you eliminate the cause, the error will disappear by itself? The problem is that the error will not go away even if you carry out the repair absolutely correctly. If you don’t reset the settings, the code will continue to hang, preventing the machine from starting to work. How to clear an error on a Bosch machine?
- Turn the program selector to the off position.
- Turn the selector to spin. At this stage, you need to wait until the error appears on the control panel again.
- Press and hold the button responsible for switching the drum speed for a few seconds, then release it.
- Rotate the program switch to set the “drain” mode.
- Press the speed switch button again and wait a few seconds.
If all the lights blink together and the machine beeps loudly, then everything went well and the error has been cleared. But if after the last time you released the speed switch button, nothing happened, then you need to repeat the above steps, since it was not possible to reset the error.
We wrote above that the Bosch error F21 can be caused by some foreign object that got into the tank and this, by the way, is not at all uncommon. What our craftsmen do not extract from the depths of the washing tanks of machines: coins, pins, bra underwires, buttons, small parts from children's toys.
All this poses a danger to the parts of the washing machine, because there have been cases when sharp objects, wedged between the tank and the drum, pierced the tank and caused a leak.
How can you make sure that the drum is jammed by a foreign object without disassembling the washing machine? You need to open the hatch door of the previously switched off machine and twist the drum by hand. If you hear a metallic grinding sound and the drum jams as it rotates, then something has actually gotten into the tank. The foreign object needs to be pulled out urgently; how to do this is described in detail in the article A bra wire got into the washing machine.
If a Bosch machine refuses to wash and issues code F21 not because of a breakdown of any part or because of a foreign object, but because of a strong voltage drop in the electrical network, then more radical measures will have to be taken. The fact is that if in the locality in which you live there are problems with the electrical network and changes occur frequently, you need to protect the washing machine with voltage stabilizer. Otherwise, another such drop can burn out all the electronics of the machine and this will definitely send your “home assistant” to the trash heap.
To summarize, we note that error code F21 on a Bosch washing machine is quite common and its causes are varied. We tried to describe the main ones. We hope the information presented will be useful to you. Happy renovation!
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Thank you for the article. They helped me figure out the motor, and the description of how to reset the error was especially helpful.
Thank you. It helped!
Thank you so much!!!
Thanks for the help. Good luck to you.
Simple and clear! Well done!
Thank you very much to the junior and senior researchers!
Thank you very much for the video! It helped.
Happened. Without removing the cover. Thank you.
For clearing errors. Well done, man!