How to fix error E21 on a Bosch dishwasher

Bosch error E21 Modern dishwashers have fairly well-functioning self-diagnosis systems, the database of which contains not unified, but highly specialized codes that make it possible to more or less accurately identify a particular breakdown. In this case, you can often talk about a breakdown even before disassembling the dishwasher. A striking example: error E21 in a Bosch dishwasher. Having seen this error, we can confidently say that there are problems with the pump, although the nature of the breakdown may be different. Let's discuss this.

Why does the code appear?

Code E21, as soon as it appears on the display of a Bosch dishwasher, immediately paralyzes its operation. The washing program stops, and the user is forced to put up with unwashed dishes and dirty water that has not been drained. Why does this code appear at all?

There is a serious blockage in the pump area. The blockage paralyzes the operation of this part, making draining water impossible or at least difficult.
The pump impeller is damaged or badly worn. Also, the E21 code may “pop up” if large debris is clogged in the impeller.

Often, difficulties in rotating the impeller appear when hair or threads are wound around it.

Problems have arisen with the rotor, causing it to stop rotating or significantly lose speed. This usually happens when a part has reached an extreme level of wear.

It is important to remember that error E21 appears in cases where the control module recognizes the pump and can control it, but thanks to a special algorithm it understands that this part is not working satisfactorily. It happens that it appears first error E23 for Bosch dishwasher, then this error begins to alternate with code E21 (after a reboot). This behavior of the dishwasher once again confirms the formation of a blockage close to the pump, but we will talk about this in the next paragraph.

Pump clogged

Bosch dishwasher error So, we have understood in general terms the reasons for the appearance of the E21 code, now the brain requires details. Let's start with blockages located near the pump or inside the part. Unfortunately, it is impossible to get to the clogged pump without disassembling the machine, but you can try cleaning the garbage filter and then restarting the dishwasher. It is quite possible that water, passing again through a clean filter, will break through a deeper blockage. If this does not happen, we will disassemble the dishwasher to get to its internal parts.

How to disassemble the machine to get to the parts located in the pan, including the pump, is described in the article How to fix error E14 in a Bosch dishwasher, let's not repeat ourselves. To remove the pump, which is located on the body of the circulation module, you need to grasp its body with one hand and turn this part counterclockwise. After this, it can be easily removed. You will also need to disconnect the plug with wires from the pump body.

Next, we take a rag, wrap it around our finger and begin to remove dirt from the niche in which the pump stood. After such cleaning, sometimes you end up with a good handful of tightly crumpled food scraps, which, among other things, also smell bad. After cleaning the seat and checking how the impeller on the pump rotates, you can return the part to its place and reassemble the dishwasher in the reverse order.

Impeller problems

Removing the pump may reveal that the impeller is severely worn and cannot perform its intended function.This is one of the most noticeable breakdowns, since a broken impeller can be recognized from afar, because its blades will be a pity to look at. The impeller on the pumps of Bosch dishwashers is removable, it is quite possible to change it, however, finding this part on sale is very, very difficult.

You can try to buy this part somewhere for analysis, but we repeat once again, the chances are slim. Some people suggest restoring the old impeller by soldering missing or broken blades to it, but we are supporters of quality repairs, so we suggest you buy and install a new drain pump.

A new pump will cost at least $33, but at least you'll save on labor.

It happens that the blades on the pump impeller are not damaged at all, but a whole skein of some kind of threads, hair mixed with compressed food remains hangs on them. Under such conditions, the impeller cannot operate normally and must be cleaned. Once the cleaning is complete, feel free to reassemble the dishwasher and put it back into use.

Rotor jam

When assembling modern Bosch dishwashers (especially cheap models), rather low quality spare parts are used. This makes itself felt, because the average service life of new machines is much shorter than that of the same units produced 7-10 years ago. Speaking specifically about pumps, experts note a lack of lubrication in their rotors. It seems that the manufacturer deliberately saved lubricant so that the part would fail earlier and dishwasher owners would buy spare parts for it sooner.

After some time, a poorly lubricated rotor begins to jam and rotate poorly, and this in turn becomes the cause of error E21. How can I fix this problem?

We purchase special rotor lubricant for electric pumps.
We remove the impeller from our pump.
Lubricate the rotor according to the instructions on the lubricant tube.
We put the impeller in place and check its rotation.

That's all. Now you can put the “reanimated” pump in place and assemble the dishwasher in order to check its operation. Most likely, after repair, your dishwasher will last for a long time. Good luck!