Medium Lockout
F8 on Glow-worm 30ci Plus

Your boiler has detected a sensor problem with the small internal tank used to provide instant hot water, which may cause your hot water to stay cold or be inconsistent.

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

Micro-accumulation vessel NTC fault

What causes this fault?

This fault occurs when the temperature sensor attached to the boiler's internal hot water tank fails or sends an unreadable signal to the main control board. The most common reason is that the sensor has physically degraded over time or a loose electrical connection has developed in the internal wiring.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F1View →F2View →F9View →

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