Error code
Bosch Dishwasher E12 — Code Meaning
Limescale affecting the heat pump. This definition comes from the manufacturer’s US guidance. Confirm applicability in the exact UK model manual before using it; regional equipment and code systems can differ.
Quick answer
E12: Limescale affecting the heat pump
Meaning
Limescale affecting the heat pump
First safe check
Photograph the full display, including alternating characters and suffixes.
Stop if
The warning remains, the appliance is not operating normally, or the next step requires internal access.
Who to call
Contact Bosch support or a qualified appliance technician if the warning remains, the code is not explained in the matching manual, or any internal investigation is required.
Internal diagnosis and repair require a qualified professional. Follow only the model-approved user actions described below. Follow the model’s isolation instructions before permitted maintenance. Do not reach wet or damaged electrical parts to unplug the appliance.
What does this error code mean?
Limescale affecting the heat pump.
This definition comes from the manufacturer’s US guidance. Confirm applicability in the exact UK model manual before using it; regional equipment and code systems can differ.
The reported condition does not, by itself, establish which part needs replacement.
Why is this happening?
- The manufacturer describes: limescale affecting the heat pump. The underlying cause requires assessment on the actual model.
Safe next steps
- Photograph the full display, including alternating characters and suffixes.
- Record the full model from accessible paperwork or an external label; do not dismantle the appliance to find it.
- Match the source below to your exact model manual before following any code-specific instructions.
- If the warning persists, the model is uncertain or the next step requires internal access, stop and contact Bosch support or a qualified appliance technician.
Can I fix this myself?
NoUse only the external checks described here. The code alone does not justify a parts replacement.
Safety boundary: Do not remove panels, test wiring, force a locked door or bypass a protective device.
What not to do
- Do not remove panels, test wiring, force a locked door or bypass a protective device.
- Do not repeatedly reset an unexplained or returning warning, or buy parts solely from this display.
When to call a technician
Contact Bosch support or a qualified appliance technician if the warning remains, the code is not explained in the matching manual, or any internal investigation is required.
Safety warning
Stop if there is leakage, a burning smell, unusual heat or electrical tripping. Keep clear of wet electrical connections. Do not remove panels, test wiring, force a locked door or bypass a protective device.
Useful hub links
Other Bosch dishwasher codes
Bosch Dishwasher E03 — Code Meaning
Main control-board relay fault
Bosch Dishwasher E04 — Meaning and Safe Advice
Heater-electronics self-test fault in Bosch US guidance
Bosch Dishwasher E05 — Meaning and Safe Advice
Wash-arm diverter control-circuit fault in Bosch US guidance
Bosch Dishwasher E10 — Code Meaning
Zeolite drying-chamber heater fault
Relevant guide
Frequently asked questions
Does E12 identify a failed part?+
No. A code describes a reported condition, and the correct model documentation is needed before diagnosis.
Does this apply to every model?+
This definition comes from the manufacturer’s US guidance. Confirm applicability in the exact UK model manual before using it; regional equipment and code systems can differ.
Sources and review status
Model dependent · Last reviewed 21 September 2026
- Bosch US dishwasher code reference
manufacturer support · other · checked 21 September 2026
Limescale affecting the heat pump. This definition comes from the manufacturer’s US guidance. Confirm applicability in the exact UK model manual before using it; regional equipment and code systems can differ.