Error F21 in a Bosch washing machine
If your Bosch washing machine has ever displayed the F21 error code without tripping any circuit breakers or fuses, you're in luck. If this error occurs, technicians strongly recommend immediately unplugging the Bosch washing machine before calling a technician. Trying to resolve the issue yourself, especially with the appliance running, can lead to electric shock. However, we won't scare you ahead of time; let's address this error step by step.
Interpretation and description of code
Error F21 in a Bosch washing machine can appear not only as an alphanumeric code, but also as a series of flashing lights on the control panel. This is because some Bosch washing machine models lack a display, meaning there's nowhere to display the F21 code.
Dozens of errors can be identified by the system of flashing indicators. Technicians do this offhand, as they have extensive experience working with such machines. Users can also do this using a special error code table.
The image below shows how the F21 code is displayed on Bosch washing machines without a display. The following occurs: the washing machine freezes, stops responding to button presses and program selector knob movements, and three lights—1000 RPM, 800 RPM, and Rinse—start flashing or illuminating simultaneously. If you have an older model washing machine that spins at a maximum of 800 RPM, the 800 RPM, 600 RPM, and Rinse lights will also light.
The explanation for 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: the drum of the Bosch washing machine cannot rotate. Upon closer inspection, the washing machine attempts to spin several times, and if it fails, the F21 code appears on the control panel. What caused this code, and why was the washing machine unable to spin the drum?
- The tachometer sensor is faulty. The control module isn't receiving engine speed information, meaning it simply stops the Bosch washing machine and displays the F code.
- The motor has failed. If the motor is broken, it can't rotate the drum. Consequently, after several attempts to start the motor, the module displays the error message.
- An open circuit in the circuit supplying the motor or Hall sensor (tachometer). In this case, the sensor and motor are working properly, but the wiring supplying them is broken or the contacts are corroded.
- The cause of the F12 error may be a foreign object that accidentally got into the drum during washing and jammed the drum.
- The F12 code may also appear due to a drop in voltage in the electrical network.
The Hall sensor is faulty
Having deciphered the F12 error and identified its causes, we ask ourselves new questions: how to fix the problem that generated the code, and most importantly, how to quickly detect it, preferably without calling a technician. There are no universal troubleshooting solutions; you need to start checking all the above-mentioned causes in your own order until you find the problem.
Let's start with the Hall sensor. Please understand that we chose this testing order not for practical reasons, but to better structure the article. You'd likely choose a different order—from simple to complex—and that would be perfectly reasonable. For example, first check to see if any foreign objects are obstructing the drum's rotation, then check the power supply, and only then delve into the housing to test the motor and Hall sensor.
But let's not digress. Right off the bat, we encountered a challenge related to accessing the tachometer and motor of a Bosch washing machine. How do you get to these components?
- Slowly turn off the washing machine and take it out somewhere with more free space.
- We dismantle the back wall of the washing machine housing, after which we remove the drive belt, which will certainly get in the way.
- We take a photo of the location of the wires and fasteners on our phone so as not to mix anything up later and remove the engine.
To quickly remove the motor from a Bosch washing machine, you must first disconnect the connectors with wires from the motor, then unscrew the retaining bolts, then press on the body of the part so that it moves forward slightly, and pull it down.
The tachometer is located directly on the engine housing, so we need to remove it and inspect it carefully. There may be traces of oxidation and grease on the inner surface of the tachometer ring; these must be removed. Next, take a multimeter and check the Hall sensor. If the tachometer is burned out, it will need to be replaced immediately.
Engine problems
The Bosch Maxx 5 washing machine, as well as other Russian-assembled models, are often reported at service centers for serious motor problems. The most common problem is a problem with the brushes. Brushes on commutator motors wear out quite often, and replacing them is a routine task for a mechanic. An amateur will have to tinker with the brushes a little, but this repair is still considered simple, so you can do it yourself, especially if you read our publication How to change brushes on a Bosch washing machine?
Things will be much worse if the motor is leaking current to the housing or if several winding turns are broken. In this case, the entire motor will 99% of the time need to be replaced. At the very least, it will be cheaper than rebuilding the old motor. But let's not dwell on the sad stuff; first, we need to check everything. We set up our device (multimeter) and check the housing for leaks. If there is no leak, we check each winding turn, trying to detect a breakdown. This is painstaking work, but it will allow us to accurately determine whether the motor is working properly.
Other malfunctions
Before we move on to other malfunctions that cause the F21 error, let's figure out how to reset the error on a Bosch washing machine. You might be wondering, why reset the error at all? After all, if you fix the problem, the error will go away on its own. The problem is, the error won't go away, even if you perform the repairs perfectly. If you don't reset the settings, the code will remain, preventing the machine from starting. How do you reset the error on a Bosch washing machine?
- Turn the program selector to the off position.
- Turn the selector dial to spin. At this point, 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.
- Turn the program selector to the “drain” mode.
- Press the speed switch button again and wait a few seconds.
If all the lights blink in unison and the machine beeps loudly, then everything went well and the error has been cleared. But if nothing happened after you released the speed switch button for the last time, then you need to repeat the above steps, since you were unable to reset the error.
We mentioned above that the F21 error in Bosch washing machines can be caused by a foreign object lodged in the drum, and this, by the way, is not uncommon. Our technicians have retrieved all sorts of objects from the depths of washing machine drums: coins, pins, bra underwires, buttons, and small parts from children's toys.
All of this poses a danger to the washing machine's components, as there have been cases where sharp objects, wedged between the tank and the drum, have pierced the tank and caused a leak.
How can you tell if a foreign object is jamming the drum without disassembling the washing machine? Open the door of the machine after turning it off and rotate the drum manually. If you hear a metallic grinding sound and the drum jams while rotating, then something has indeed gotten into the drum. The foreign object must be removed immediately; this is described in detail in the article.A bra underwire got into the washing machine..
If your Bosch washing machine refuses to wash and displays the F21 error code, not because of a broken part or a foreign object, but because of a significant power surge, you'll need to take more drastic measures. If your area has power supply issues and frequent power surges, you'll need to protect your washing machine withvoltage stabilizerOtherwise, another such surge could burn out all the machine's electronics, which would definitely send your "home assistant" to the trash.
To summarize, the F21 error code on Bosch washing machines is quite common and has a variety of causes. We've tried to cover the main ones. We hope you find this information helpful. Happy repairing!
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Thanks for the article. It helped me understand the engine, and the description of how to reset the error was especially helpful.
Thank you. It helped!
Thank you very much!!!
Thank you for your help. Good luck to you.
Simple and clear! Well done!
Thank you very much to the junior and senior research fellows!
Thank you so much for the video! It helped.
It worked. Without removing the lid. Thank you.
For clearing the errors. Well done, man!