Low
S.109 on Glow-worm Energy7 System

Your boiler is currently in a temporary sleep mode and is functioning exactly as it should.

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

Product's standby mode activated

From this model's manual
Verified against the Glow Worm/Glow Worm Energy7 System installation & service manual, page 50.
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 external heating controls or room thermostatIncrease the temperature or schedule setting on your programmerWait for the boiler to wake up once a heating or hot water demand is triggered

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

Avoid the next call-out bill

Monthly cover means no unexpected bills when your boiler breaks down.

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

S.108View →

All 95 fault codes on the Energy7 System

Seeing a different code? Every code this model can display, in one place.

ConnectionF.00F.01F.10F.11F.13F.20F.22F.23F.24F.25F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.76F.77F.78F.83F.84F.85F.86F.87F.88F.89F.91F.97F22P.01P.02P.03P.04P.05P.06P.07P.10S.0S.01S.02S.03S.04S.05S.06S.07S.08S.10S.11S.13S.14S.15S.16S.17S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.33S.34S.39S.41S.42S.46S.53S.54S.76S.88S.91S.96S.97S.98S.99S.108

Related guides you might find useful

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 →

New boiler cost 2026

Realistic UK prices for a swap.

Read →