BoilerFaultCodes.com
E384 High Lockout

Your boiler thinks a flame is present even when it should be off, causing it to shut down for safety.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: False flame

What causes this fault?

This fault occurs when the boiler's internal sensors detect a flame signal even though the gas valve should be closed and the burner turned off. It is usually caused by a faulty sensing electrode sending a false signal or a control board malfunction that misinterprets electrical interference as a live flame.

This fault can sometimes be more common in damp or cold seasons, as high humidity or moisture ingress into the casing can cause electrical trackage and false readings on the circuit board.

Typical repair cost £120-350 (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 →

Protect yourself from future repair bills

A boiler cover plan would cover faults like E384 — no call-out fees, no surprises.

Top rated
OpenFix
Boiler & heating care plans
Get a quote →
Hometree
from £12.95/month
Get a quote →
HomeServe
from £8.00/month
Get a quote →

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

Could it be time for a new boiler?

If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.

UK's #1 online installer
Boxt
Fixed-price online quotes. Next-day installation.
Get a free quote →
Heatable
Instant online boiler quotes from £1,499.
Get a free quote →
iHeat
Fast installation. Price match guarantee.
Get a free quote →

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

Related fault codes