How much does it cost to fix Remeha error code 18.?

Typical repair cost for the Remeha 18. fault is £150-350 including labour.

18. High

Remeha 18. Fault Code

Q: What does the Remeha 18. fault code mean?

Your boiler has switched itself off because the water inside it has become dangerously hot, likely due to a blockage in the system or a pump failure.

Also written as 18 — same fault.

The Remeha 18. fault code means: your boiler has switched itself off because the water inside it has become dangerously hot, likely due to a blockage in the system or a pump failure.. It appears on 3 Remeha models in our database.

Technical description: Max. water temperature. Flow temperature too high.

Typical repair cost £150-350 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Remeha models that show the 18. fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Remeha 18. fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026