Bosch Dishwasher Error E12: What It Means and How to Fix It
Short answer
E12 on a Bosch dishwasher means: limescale build-up in the heat pump / heating system. First step: Descale the dishwasher with Bosch's descaler (available from Bosch).
Limescale in the heat pump
Likely causes
- Limescale deposits in the heating system
How to fix it
- 1Descale the dishwasher with Bosch's descaler (available from Bosch).
- 2If the model has a water softener, use softening salt.
When to call a professional: If the code returns after descaling.
Applies to: Bosch dishwashers
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Source
Based on Bosch's official error code information: Bosch US – Dishwasher Error Codes. Last checked 2026-10-28. Codes and their meaning can differ by model and region; check your appliance's manual.
Frequently asked questions
What does Bosch dishwasher error code E12 mean?
Limescale build-up in the heat pump / heating system.
How do I fix E12 on a Bosch dishwasher?
Descale the dishwasher with Bosch's descaler (available from Bosch). If the model has a water softener, use softening salt.
When should I call a technician for E12?
If the code returns after descaling.