What E21 means
The circulation (heat) pump is blocked.
Also shown as: E:21, depending on the model.
Likely causes
- Debris in the pump
- Pump fault
Safe first checks
- Turn the breaker off for 30 seconds and back on.
When to stop
If not resolved, contact Bosch support.
Checked against: Bosch USA: Bosch dishwasher error codes troubleshooting guide. Codes can differ by model and year, so confirm with your owner's manual.