Sime Ecomfort Plus HE Fault codes & diagnostics

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

CombiSystem Natural Gas 2005-2014 Discontinued
GC Numbers 41-283-1047-283-13
Download the Sime Ecomfort Plus HE manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

This boiler uses LED flash patterns

Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
6 High
Just want the most common Sime Ecomfort Plus HE faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 6 documented codes

Tap any card for details

LED / flash-pattern codes
Flashing orange LED

Your boiler is struggling to detect a flame, which means it will shut down for safety to prevent gas from flowing without being burned.

High Engineer only £120-£240

Parts commonly replaced

  • Ignition electrode
  • Detection (ionisation) electrode
  • Ignition lead
  • Gas valve

Related codes

Full explanation for Flashing orange LED
Digital codes
Red LED after flow switch

Your boiler has detected that water is not circulating correctly through the system, causing it to shut down to prevent overheating.

High DIY-safe £120-350

What to check first

  1. Check that the boiler pressure is between 1 and 1.5 bar on the pressure gauge
  2. Ensure all radiator valves are fully open to allow water to flow
  3. Check if any external valves on the pipework leading to the boiler have been accidentally closed

Parts commonly replaced

  • Circulation Pump
  • Water Flow Switch
  • Overheat Thermostat (Limit Stat)

Related codes

Full explanation for Red LED after flow switch
Red LED on (solid)

Your boiler has stopped working because it failed to light the flame after several attempts, usually due to a temporary interruption in the gas supply or a dirty ignition part.

High DIY-safe £90-250

What to check first

  1. Check that your gas emergency control valve is open and you have credit on your gas meter (if applicable).
  2. Turn on another gas appliance, such as a hob, to ensure gas is flowing to the property.
  3. Press and release the reset button on the front of the boiler panel to restart the ignition sequence.

Parts commonly replaced

  • Ignition electrode
  • Flame sensing probe
  • Gas valve

Related codes

Full explanation for Red LED on (solid)
Status & diagnostic codes

5 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

G20 Diagnostic Your boiler is displaying a technical configuration code indicating it is calibrating or checking the gas pressure supply to the burner. G30 Diagnostic Your boiler is struggling to correctly adjust the amount of gas it uses to heat your home, meaning it cannot operate safely or efficiently. G31 Diagnostic Your boiler is detecting an issue with the pressure of the gas being supplied to the burner, which is preventing it from firing up safely. JP4 Diagnostic Your boiler has detected an incorrect fuel type setting for the gas supply it is receiving, which prevents it from igniting safely. Orange LED on Status Your boiler is currently in standby mode and is working exactly as it should while waiting for a request for heating or hot water.