How much does it cost to fix Keston error code 78?

Typical repair cost for the Keston 78 fault is £150-350 including labour.

78 High

Keston 78 Fault Code

Q: What does the Keston 78 fault code mean?

Your boiler was running but the flame went out unexpectedly, so it has safely shut itself down to prevent any gas issues.

The Keston 78 fault code means: your boiler was running but the flame went out unexpectedly, so it has safely shut itself down to prevent any gas issues.. It appears on 1 Keston model in our database.

Technical description: FLAME LOSS

Typical repair cost £150-350 (including labour)

Engineer required

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

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 78: no call-out fees, no surprise bills.

Approved partner

Domestic Appliance Guard

Unlimited call-outs, 24/7 helpline, no price-hike promise

Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Keston models that show the 78 fault code

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

Heat 45 Repair: £150-350

Source

Keston 78 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.

Keston Heat 45 manual (PDF)

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026