Medium
ALL 03 on Sime Murelle Advanced HE MkII Combi

Your boiler has detected that there is too much water inside the heating system, causing the pressure to rise above the safe limit.

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

High water pressure in system

From this model's manual
Verified against the Sime Murelle Advanced He Combi installation & service manual, page 32.
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

Locate a radiator in your home that has a bleed valve.Place a cloth and a container under the valve.Open the valve slightly with a radiator key to let water out until the pressure gauge on the boiler drops back into the green zone (usually 1.0 to 1.5 bar).Close the valve tightly.

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