Medium
ALL 03 on Sime Murelle Elite HE Combi

Your boiler has detected that the water pressure inside your heating system is too high for it to operate safely.

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 SYSTEM PRESSURE ALARM

Shared across the Murelle Elite HE 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

Locate a radiator in your home, preferably on the ground floor.Place a cloth or small container under the radiator bleed valve.Slowly open the valve to release water until the pressure gauge on the boiler shows between 1 and 1.5 bar, then tighten the valve firmly.

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Related fault codes

AL 02View →

All 21 fault codes on the Murelle Elite HE Combi

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

ALL 02ALL 04ALL 05ALL 06ALL 07ALL 08ALL 09ALL 10ALL 14ALL 15ALL 20ALL 21ALL 22ALL 23ALL 24ALL 25ALL 26ALL 27ALL 28ALL 29

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