How much does it cost to fix Ideal error code b18?

Typical repair cost for the Ideal b18 fault is £120-250 including labour.

b18 High

Ideal b18 Fault Code

Q: What does the Ideal b18 fault code mean?

Your boiler is temporarily pausing because it is struggling to move water through the system, often due to a blocked filter or a trapped air pocket.

Also written as B18 — same fault.

The Ideal b18 fault code means: your boiler is temporarily pausing because it is struggling to move water through the system, often due to a blocked filter or a trapped air pocket.. It appears on 1 Ideal model in our database.

Technical description: Blocking code (appears alternating with 9)

Typical repair cost £120-250 (including labour)

Engineer required

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

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Ideal models that show the b18 fault code

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

Imax W Repair: £120-250

Source

Ideal b18 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.

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