How to fix the E21 error on a Bosch dishwasher

Modern dishwashers have fairly well-established self-diagnostic systems, whose databases contain highly specialized codes rather than standardized ones, allowing for a more or less precise identification of a particular fault. Often, the fault can be detected even before disassembling the dishwasher. A prime example is the E21 error in a Bosch dishwasher. Seeing this error code indicates a pump problem, although the nature of the fault can vary. Let's discuss this.

Why does the code appear?

The E21 code, as soon as it appears on the Bosch dishwasher's display, paralyzes its operation. The washing program stops, and the user is forced to deal with unwashed dishes and un-drained dirty water. Why does this code appear in the first place?

1. A serious blockage has formed in the pump area. The blockage paralyzes the operation of this component, making water drainage impossible or at least difficult.
2. The pump impeller is damaged or severely worn. The E21 code may also pop up if the impeller is clogged with large debris.

Often, difficulties in the rotation of the impeller appear when hair or threads get wrapped around it.

3. The rotor is experiencing problems, causing it to stop rotating or significantly lose speed. This usually occurs when the part is worn to an extreme degree.

It's important to remember that the E21 error occurs when the control module recognizes the pump and can control it, but thanks to a special algorithm, it understands that this component is not working satisfactorily. It can happen that the error appears first. Bosch dishwasher error E23, then this error begins to alternate with the E21 code (after a reboot). This behavior of the dishwasher once again confirms a blockage near the pump, but we'll discuss this in the next section.

Pump clogged

So, we've covered the general causes of the E21 code, but now the brain demands more details. Let's start with blockages located near the pump or inside the component. Unfortunately, it's impossible to get to the clogged pump without disassembling the machine, but you can try cleaning the debris filter and then restarting the dishwasher. It's quite possible that the water, passing through the clean filter again, will clear a deeper blockage. If this doesn't happen, we'll have to disassemble the dishwasher to access its internal components.

The article explains how to disassemble the machine to get to the parts located in the pan, including the pump. How to fix the E14 error on a Bosch dishwasherWe won't repeat ourselves. To remove the pump, which is located on the circulation module housing, grasp its housing with one hand and turn this part counterclockwise. After this, it will easily come off. You will also need to disconnect the plug and wires from the pump housing.

Next, take a rag, wrap it around your finger, and begin cleaning the dirt from the niche where the pump was located. After such cleaning, you sometimes end up with a good handful of tightly crumpled food debris, which, among other things, smells bad. After cleaning the seat and checking the rotation of the impeller on the pump, you can replace the part and reassemble the dishwasher in reverse order.

Impeller problems

Removing the pump may reveal that the impeller is severely worn and unable to perform its intended function. This is one of the most noticeable failures, as a broken impeller can be identified from afar, as its blades are a real eyesore. The impeller on Bosch dishwasher pumps is removable and can be replaced, although finding this part for sale is quite difficult.

You can try to buy this part at a salvage yard, but again, the chances are slim. Some suggest restoring the old impeller by soldering missing or broken blades, but we're committed to quality repairs, so we recommend purchasing and installing a new drain pump.

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

Sometimes, the impeller blades on the pump are undamaged, but instead, a whole skein of threads, hair, and compacted food remains clings to them. Under these conditions, the impeller cannot operate properly and must be cleaned. Once cleaning is complete, reassemble the dishwasher and restart it.

Rotor jamming

When assembling modern Bosch dishwashers (especially lower-end models), they use rather low-quality parts. This is noticeable, as the average lifespan of new machines is significantly shorter than that of similar units manufactured 7-10 years ago. Specifically, regarding the pumps, technicians note a lack of lubrication in their rotors. It seems the manufacturer intentionally skimped on lubrication to ensure early failure and prompt owners to buy replacement parts sooner.

A poorly lubricated rotor will start to jam and rotate poorly after a while, which in turn causes the E21 error. How to fix this problem?

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

That's it. Now you can reinstall the "revived" pump and reassemble the dishwasher to test it out. Chances are, after the repair, your dishwasher will continue to serve you well for many years to come. Good luck!

   

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