Medium Warning
6.8 on Worcester Bosch Greenstar 25 HE Combi

Your boiler is confused by how long it is taking to heat your hot water and is stuck in a constant cycle.

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.

Technical description

Constant hot water cycle time

What causes this fault?

This fault occurs when the boiler detects that it is taking far too long to reach the required temperature for your hot water, causing it to get stuck in a repetitive heating loop. It is usually caused by a faulty sensor sending incorrect temperature readings to the brain of the boiler or a mechanical part failing to direct heat to the water properly. In some cases, the main control board may simply be misinterpreting the data it receives from the system.

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 →

Related fault codes

EAView →D1View →E9View →

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →