How much does it cost to fix Keston error code E 03?

Typical repair cost for the Keston E 03 fault is £150-300 including labour.

E 03 Emergency

Keston E 03 Fault Code

Q: What does the Keston E 03 fault code mean?

Your boiler is failing to detect the flow of gas required to ignite the burners, meaning it cannot safely produce heat or hot water.

Also written as E03 — same fault.

The Keston E 03 fault code means: your boiler is failing to detect the flow of gas required to ignite the burners, meaning it cannot safely produce heat or hot water.. It appears on 3 Keston models in our database.

Technical description: Gas valve faulty or not connected

Typical repair cost £150-300 (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 E 03 fault code

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

C40 Repair: £80-150
C55 Repair: £250-450
C90 / C110 Repair: £150-300

Source

Keston E 03 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