d.27 Low

Glow-worm d.27 Fault Code

Also written as D27 — same fault.

The Glow-worm d.27 fault code means: your boiler is displaying an internal status code that indicates a software or configuration setting is not currently being used, which should not affect the daily operation of your heating or hot water.. It appears on 6 Glow-worm models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Option Relay 1 Reserved for future use

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 d.27: 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.

Glow-worm models that show the d.27 fault code

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

Source

Glow-worm d.27 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.

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