Sime iQE Comfort 30 Fault codes & diagnostics

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

Combi Natural Gas 2013 onwards Discontinued
GC Number 47-283-47
Download the Sime iQE Comfort 30 manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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15 High
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-283-47 Comfort 30 2013–present

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

Just want the most common Sime iQE Comfort 30 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 15 documented codes

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AL 02

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

High DIY-safe £0-£120

What to check first

  1. Locate the filling loop (a silver braided hose) underneath the boiler.
  2. Open the small valve(s) on the filling loop to allow cold mains water into the system.
  3. Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).
  4. Close the valve(s) tightly and ensure the boiler resets.

Parts commonly replaced

  • Pressure Relief Valve
  • Pressure Sensor
  • Expansion Vessel

Related codes

Full explanation for AL 02
AL 05

Your boiler has lost the ability to measure the temperature of the water being sent to your radiators, so it has shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • Central Heating NTC Sensor
  • Wiring Harness

Related codes

Full explanation for AL 05
AL 06

Your boiler has stopped working because it failed to light the flame properly, likely due to an issue with the gas supply, the ignition process, or the exhaust system.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Condensate trap

Related codes

Full explanation for AL 06
AL 07

Your boiler has detected that it has become dangerously overheated and has shut itself down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Safety thermostat
  • Pump
  • Diverter valve
  • Heat exchanger

Related codes

Full explanation for AL 07
AL 08

Your boiler has failed to light because it cannot detect a flame, so it has safely shut down to prevent gas from building up.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Ionisation probe
  • Gas valve
  • PCB

Related codes

Full explanation for AL 08
AL 10

Your boiler is struggling to detect the temperature of your hot water, so it has safely shut down to prevent the system from overheating.

High Engineer only £120-200

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor

Related codes

Full explanation for AL 10
AL 13

Your boiler has detected that the flue gases are overheating, so it has safely shut itself down to prevent potential damage.

High Engineer only £120-250

Parts commonly replaced

  • Exhaust temperature sensor
  • NTC sensor
  • Primary heat exchanger

Related codes

Full explanation for AL 13
AL 14

Your boiler has detected an issue with the sensor that monitors the heat of the gases leaving your system, which prevents the boiler from running to keep it safe.

High Engineer only £120-200

Parts commonly replaced

  • Flue temperature sensor
  • Wiring harness

Related codes

Full explanation for AL 14
AL 15

Your boiler has detected that the internal mechanism responsible for venting exhaust gases is not spinning correctly, causing the system to stop working as a safety precaution.

High Engineer only £150-300

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

Full explanation for AL 15
ALARM 02

Your boiler has detected that the water pressure is too low, which prevents it from heating up or providing hot water.

High DIY-safe £0-120

What to check first

  1. Locate the silver filling loop cable underneath your boiler.
  2. Slowly open the valve(s) to allow water into the system while watching the pressure gauge.
  3. Close the valve(s) firmly once the pressure gauge needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for ALARM 02
ALARM 05

Your boiler has detected a problem with its temperature sensor and has stopped working as a safety precaution.

High Engineer only £90-160

Parts commonly replaced

  • Central heating NTC temperature sensor
  • Connecting wiring harness

Related codes

Full explanation for ALARM 05
ALARM 06

Your boiler has stopped working because it cannot light the gas flame needed to provide heat and hot water.

High DIY-safe £120-280

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. If you have a pre-payment meter, check that you have sufficient credit
  3. Press the Reset button on the control panel to see if the boiler restarts

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Ignition Lead

Related codes

Full explanation for ALARM 06
ALARM 07

Your boiler has likely overheated or has air trapped inside, causing it to shut down for safety.

High DIY-safe £100-250

What to check first

  1. Locate the reset button on your boiler control panel and press it once
  2. Check that your radiator valves are open to ensure water can flow properly
  3. Bleed your radiators using a radiator key to remove any trapped air from the system

Parts commonly replaced

  • Safety limit thermostat
  • Circulation pump
  • Overheat sensor (NTC)

Related codes

Full explanation for ALARM 07
ALL 06

Your boiler has detected a serious internal fault that has caused it to shut down for safety reasons and it will not provide heating or hot water until a professional has inspected it.

High Engineer only £150-350

Parts commonly replaced

  • Main PCB
  • Wiring Harness
  • Ionisation Electrode

Related codes

Full explanation for ALL 06
ALL 10

Your boiler is struggling to detect the temperature of your hot water, which means it will likely stop providing hot water until the faulty sensor is replaced.

High Engineer only £120-200

Parts commonly replaced

  • DHW NTC Sensor
  • Wiring harness

Related codes

Full explanation for ALL 10