How much does it cost to fix Keston error code F0?

Typical repair cost for the Keston F0 fault is £120-250 including labour.

F0 High

Keston F0 Fault Code

Q: What does the Keston F0 fault code mean?

Your boiler's main control computer is missing a vital activation chip, which means the system cannot start up or provide any heat.

The Keston F0 fault code means: your boiler's main control computer is missing a vital activation chip, which means the system cannot start up or provide any heat.. It appears on 8 Keston models in our database.

Technical description: Boiler Chip Card (BCC) not fitted

What causes the Keston F0 fault?

This fault occurs when the boiler's main control board cannot detect the unique memory chip that tells it how to operate safely. The most common reason is that the chip card has vibrated loose, failed electronically, or was not correctly transferred when a technician replaced the circuit board.

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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Keston models that show the F0 fault code

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

Source

Keston F0 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.

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