Er:21
What code Er:21 means on a Bosch washing machines, what causes it, and which part to check first.
● SEVERITY: MEDIUM
Bosch Er:21 means: Excessive foam detected. The documented cause is: Use the proper amount of high-efficiency (HE) detergent in the washer. Most loads need only 1 tablespoon of HE detergent due to the reduced water level in this front-load washer
What Er:21 means
Excessive foam detected
The display shows Er:21 and the machine stops until the fault is cleared.
What the technical documentation says
Causes documented in the technical source published by applianceaid.com
| DOCUMENTED CAUSE OR CHECK |
|---|
| Use the proper amount of high-efficiency (HE) detergent in the washer |
| Most loads need only 1 tablespoon of HE detergent due to the reduced water level in this front-load washer |
Replacement parts
Tools you'll need
Before you open anything
Unplug the machine and close the water tap before removing any panel. Water and mains electricity sit centimetres apart inside a washing machine. If the drum still holds water, drain it from the filter first — it can be scalding.
What to check, in order
From the quickest check to the one that needs a technician.
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Frequently asked questions
What does Er:21 mean on a Bosch?
Excessive foam detected The documented cause is: Use the proper amount of high-efficiency (HE) detergent in the washer. Most loads need only 1 tablespoon of HE detergent due to the reduced water level in this front-load washer
Can I fix Er:21 myself?
It depends on the part involved: Use the proper amount of high-efficiency (HE) detergent in the washer. Most loads need only 1 tablespoon of HE detergent due to the reduced water level in this front-load washer Clearing a filter or straightening a hose is within reach of anyone; anything behind a panel means mains electricity and water together — that is a job for a technician.
Does Bosch use other codes on this appliance?
Yes: we document 20 other codes for Bosch on this washing machines. They are listed at the bottom of this page, each with its own meaning.
Does the same code mean the same thing on other brands?
Often not. The same two characters can point to completely different faults depending on the manufacturer — always check the page for your own brand.