Medium
21 on Sime Murelle EV HE Combi

Your boiler has lost the signal from a sensor responsible for monitoring the temperature of the water heading to your radiators, meaning it cannot accurately manage your heating.

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

DELIVERY PROBE FAILURE FIRST MIXED ZONE

Shared across the Murelle EV 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.

Engineer required

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

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Related fault codes

02View →03View →04View →

All 71 fault codes on the Murelle EV HE Combi

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

01020304050607080910131415202223242526272829AL 01AL 02AL 03AL 04AL 05AL 06AL 07AL 08AL 09AL 10AL 11AL 12AL 13AL 14AL 15AL 17AL 18AL 28AL 30AL 37AL 38AL 40AL 41AL 42AL 43AL 44AL 56AL 57AL 62AL 72AL 74AL 77AL 78AL 79AL 80AL 81AL 82AL 83AL 84AL 88AL 89AL 90AL 92AL 93AL 95AL 96AL 98AL 99

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