Bosch Dishwasher E21 — What It Means & How to Fix It
E21 means the heat pump is blocked — Bosch says to reset power at the breaker for 30 seconds and to call its customer support if that does not resolve it.
What this code means
Bosch's US error-code page gives E21 as: the heat pump is blocked. On Bosch dishwashers the heat pump is the combined pump and heater that circulates and warms the wash water. Bosch's steps are a 30-second breaker reset and, if that fails, a call to Bosch Customer Support.
Bosch's US error-code page lists E21 as the heat pump being blocked. Newer models show the same condition as E6002.
Most likely causes
| Cause | How likely | DIY-fixable? |
|---|---|---|
| Heat pump blocked | Common | No — technician job |
| One-off control glitch | Occasional | Yes — breaker reset |
What you can try yourself
- Switch the dishwasher off.
- Turn its circuit breaker off for 30 seconds, then back on.
- Run a short cycle.
- If E21 returns, call Bosch Customer Support.
When to call a technician
- E21 returns after a breaker reset.
- Dishes come out unwashed and the spray arms are not turning.
- A humming or grinding noise from under the tub during the wash.
Typical professional repair cost: Heat pump replacement on a Bosch dishwasher typically runs $250–$450 including labor.
Frequently asked questions
What does E21 mean on a Bosch dishwasher?
Bosch says the heat pump is blocked. Its steps are a 30-second breaker reset, then a call to Bosch Customer Support if the code returns.
Can I clear a blocked heat pump myself?
Bosch's page gives no owner procedure for it beyond the reset. Cleaning the filter is always worthwhile, but the heat pump itself sits under the tub and is a technician's job.
Sources checked
Error meanings can vary by model. This guide was checked against the documentation above; use the manual for the model number on your own appliance when it differs.
Related Bosch codes
- Bosch Dishwasher E15 Water reached the base pan under the tub and Bosch's leak protection locked the machine — sometimes a genuine leak, often a one-off spill or condensation that clears once the base dries.
- Bosch Dishwasher E24 The dishwasher can't drain properly — start with the filter, then the drain hose path, and don't skip checking that the drain pump cover is seated.
- Bosch Dishwasher E25 The drain pump itself is blocked or its cover is loose — and Bosch makes the pump cover owner-accessible, so this is one of the most fixable codes the brand throws.
- Bosch Dishwasher E09 The heating system isn't raising the water temperature — beyond one reset, the flow-through heater is a mains-voltage part that belongs to a technician.
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