Sime Murelle EV HE 25 Combi Fault codes & diagnostics

22 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas
GC Number 47-283-17
Download the Sime Murelle EV HE 25 Combi manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
5 Emergency 7 High 5 Medium 5 Low
Fault codes

All 22 documented codes

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ALL 02

Your boiler has temporarily stopped working because the water pressure inside the heating system has dropped too low.

High DIY-safe

What to check first

  1. Locate the filling loop valves underneath your boiler.
  2. Open the valves gently to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.
  3. Close the filling loop valves tightly and check the boiler display or reset the unit if necessary.

Parts commonly replaced

  • Pressure transducer
  • Filling loop valve

Related codes

Full explanation for ALL 02
ALL 03

Your boiler has temporarily stopped working because the water pressure inside the system has become dangerously high.

Emergency DIY-safe £90-180

What to check first

  1. Locate the filling loop valves connected to your boiler and ensure they are fully closed.
  2. Bleed one or two of your radiators using a radiator key to release trapped air and lower the system pressure.
  3. Keep an eye on the pressure gauge until it drops back into the normal green zone (between 1.0 and 1.5 bar).

Parts commonly replaced

  • Pressure transducer
  • Filling loop valve
  • Expansion vessel

Related codes

Full explanation for ALL 03
ALL 04

Your boiler is having trouble reading the temperature of your hot water, which means it will still supply hot water but you may not be able to control how hot it gets.

Medium Engineer only £90-180

Parts commonly replaced

  • DHW Temperature Sensor

Related codes

Full explanation for ALL 04
ALL 05

Your boiler has lost the ability to monitor its own heating temperature because a key internal sensor has failed or disconnected.

High Engineer only £120-220

Parts commonly replaced

  • Central heating NTC temperature sensor

Related codes

Full explanation for ALL 05
ALL 06

Your boiler has stopped working because it failed to light after three attempts, usually due to a temporary interruption in the gas supply.

High Engineer only £150-300

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for ALL 06
ALL 07

Your boiler has automatically shut down because an internal safety switch detected that the water inside has become dangerously hot.

Emergency Engineer only £150-350

Parts commonly replaced

  • Safety limit thermostat
  • Automatic bypass valve
  • Circulating pump
  • PCB

Related codes

Full explanation for ALL 07
ALL 09

Your boiler has stopped working because it cannot detect water flowing through the system properly.

High Engineer only £150-350

Parts commonly replaced

  • Circulator pump
  • Flow sensor
  • Automatic bypass valve

Related codes

Full explanation for ALL 09
ALL 14

Your boiler has temporarily stopped working because it has detected a problem with the sensor that monitors the safety and temperature of the exhaust gases.

Emergency Engineer only £150-£250

Parts commonly replaced

  • Flue gas sensor
  • Wiring harness

Related codes

Full explanation for ALL 14
ALL 15

Your boiler has detected an issue with the internal fan that safely pushes waste gases out of your home, so it has temporarily stopped working to keep you safe.

High Engineer only £150-350

Parts commonly replaced

  • Flue Fan
  • Air Pressure Switch
  • Printed Circuit Board (PCB)

Related codes

Full explanation for ALL 15
Showing 11–20 of 22
ALL 20

Your boiler has temporarily shut down a specific heating zone because a safety temperature sensor detected it was getting too hot.

High Engineer only £150-300

Parts commonly replaced

  • Safety thermostat
  • Mixing valve
  • Circulating pump

Related codes

Full explanation for ALL 20
ALL 21

Your boiler has detected an issue with a temperature sensor connected to an optional underfloor heating or multi-zone kit, causing that specific heating zone to stop working safely.

Medium Engineer only £120-250

Parts commonly replaced

  • Delivery temperature probe
  • Mixed zone sensor wiring harness

Related codes

Full explanation for ALL 21
ALL 22

Your boiler is displaying an informational code because an optional multi-zone heating control board is connected, but the boiler itself is still working normally.

Low Engineer only £0-120

Parts commonly replaced

  • Mixed zone electronic board
  • Wiring harness
Full explanation for ALL 22
ALL 23

Your boiler has detected an issue with a temperature sensor connected to an optional second heating zone, though the main system is still running normally.

Low Engineer only £90-180

Parts commonly replaced

  • Delivery probe
  • NTC sensor

Related codes

Full explanation for ALL 23
ALL 24

Your boiler has detected an issue with the sensor connected to your solar panel system, but your heating and hot water will continue to work normally while this alert is on.

Low Engineer only £90-180

Parts commonly replaced

  • Solar collector temperature sensor
  • Solar sensor wiring harness

Related codes

Full explanation for ALL 24
ALL 25

Your boiler has detected a fault with the temperature sensor connected to your solar panel system.

Low Engineer only £90-180

Parts commonly replaced

  • Solar collector temperature probe (S2)
  • Wiring harness

Related codes

Full explanation for ALL 25
ALL 26

Your boiler has detected a fault with the temperature sensor connected to its optional solar heating system.

Low Engineer only £90-180

Parts commonly replaced

  • Solar collector sensor (S3 probe)
  • Wiring harness
Full explanation for ALL 26
ALL 28

Your boiler has detected an incorrect type of connection or sensor plugged into one of its internal control terminals.

Medium Engineer only £90-180

Parts commonly replaced

  • External controls
  • Wiring harness
  • Main PCB
Full explanation for ALL 28
ALL 29

Your boiler's main computer is having trouble communicating with its internal electronic boards.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness
Full explanation for ALL 29
Showing 21–22 of 22
ERROR 13

Your boiler has temporarily stopped working because it has detected an issue with the exhaust flue that removes waste gases outside.

Emergency Engineer only £100-£250

Parts commonly replaced

  • Flue gas sensor
  • Flue assembly
  • PCB

Related codes

Full explanation for ERROR 13
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