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Bosch Dishwasher E12 Error Code
Limescale buildup in the heat pump. Here is what it means and how to clear it, easiest fix first.
Hard-water scale has built up in the heat pump, the part that heats and moves the wash water. It is most common in hard-water areas, or where the built-in water softener isn't kept supplied with salt.
Newer US models show E2060. Models with a built-in water softener (common in the UK and EU, also on some US models) rely on dishwasher salt to prevent this.
How to fix Bosch E12
Run a descaling cycle
Use a dishwasher descaler, such as Bosch's own, and follow the directions on the pack. Run it with the dishwasher empty.
Top up the softener salt
If your dishwasher has a salt reservoir, fill it with dishwasher salt (not table salt) and set the water hardness in the settings to match your area. This slows down scale coming back.
Reset the dishwasher at the breaker
Switch off the dishwasher's circuit breaker, wait about 30 seconds, then switch it back on. Run a short cycle with the dishwasher empty and watch whether the same code comes back. A code that clears and stays away was likely a one-time glitch.
When to call a technician
If E12 keeps returning after descaling, contact Bosch support. The heat pump may be heavily scaled or failing.
Parts that commonly cause E12
- Heat pump (circulation pump with heater)
Order parts by your exact model number so they fit.
Other Bosch dishwasher codes
- E15Water detected in the base (leak protection)
- E24Dishwasher is not draining (blocked drain path)
- E25Drain pump blocked or pump cover loose
- E22Filter is blocked
- E23Drain pump fault
- E16 / E17Water can't enter the dishwasher
- E18Water level too low
- E14Flow meter or filling problem
- E09Heating fault (meaning varies by region)
- E27Household power supply too low
- E21Heat pump blocked
- E01-E05Control board or electronics fault
- E06Door sensor circuit fault
- E19Detergent dispenser fault
- E07 / E10CrystalDry (zeolite) drying fault
- H01Delay start is set (not an error)
Frequently asked questions
What does E12 mean on a Bosch dishwasher?
Hard-water scale has built up in the heat pump, the part that heats and moves the wash water. It is most common in hard-water areas, or where the built-in water softener isn't kept supplied with salt.
Can I fix Bosch E12 myself?
Usually, yes. Most E12 problems clear with simple checks you can do at home. Start with the first step above: run a descaling cycle.
What if E12 keeps coming back?
A code that returns after a reset and the checks above usually means a part is wearing out. Note when E12 appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.
Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.