Low
d.16 on Glow-worm Flexicom 24c / 28c

Your boiler is currently waiting for a signal from your room thermostat to tell it that your home needs heating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Status of the 24V room thermostat (ON/OFF)

From this model's manual
Verified against the Glow Worm Flexicom 24c 28c installation & service manual, page 44.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check your room thermostat is set to a temperature higher than the current room temperature.Ensure the thermostat batteries are fresh and the device has power.Verify the thermostat is not set to 'Summer' or 'Off' mode.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like d.16: 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.

Related fault codes

d.14View →d.15View →

Related guides you might find useful

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →