Medium
d.08 on Glow-worm Energy7 Combi

Your boiler is currently receiving a signal from your thermostat that it is time to heat up, but there may be a loose connection or a fault in the communication between your wall controller and the boiler.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Status of the 230V thermostat

Shared across the Energy7 range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
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 that your external room thermostat is set correctly and the batteries are fresh.Ensure the thermostat wiring at the boiler terminal block is securely connected and not loose.Power cycle the boiler by switching it off at the fused spur for one minute, then turning it back on.

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.08: 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.09View →F.70View →

All 154 fault codes on the Energy7 Combi

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

Connectiond.00d.01d.02d.04d.05d.06d.07d.09d.10d.11d.13d.14d.15d.16d.17d.18d.19d.20d.21d.22d.23d.24d.25d.27d.28d.31d.33d.34d.35d.36d.39d.40d.41d.43d.45d.47d.50d.51d.58d.60d.61d.62d.64d.65d.66d.67d.68d.69d.70d.71d.73d.75d.77d.80d.81d.82d.83d.84d.85d.88d.90d.91d.93d.94d.95d.96F.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.97F22S.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.108S.109

Related guides you might find useful

Thermostat not working

Change the batteries first, even if the screen still works.

Read →

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 →