Ariston Genus 24 RFFI Fault codes & diagnostics

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

Regular Natural Gas 24 kW Discontinued

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Just want the most common Ariston Genus 24 RFFI faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 3 documented codes

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(B) LED turning on

Your boiler has tried to ignite to provide heat but failed to detect a flame, causing the system to shut down for safety.

High DIY-safe £100-280

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. Check if other gas appliances in your home, such as a hob, are working correctly
  3. Press the 'R' or Reset button on the control panel to attempt a restart

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve
Full explanation for (B) LED turning on
(D) LED turning on

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

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the small valve(s) on the loop to allow water into the system.
  3. Watch the pressure gauge until it reaches 1.5 bar, then close the valves tightly.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure relief valve
Full explanation for (D) LED turning on
(G) LED turning on

Your boiler has switched itself off because it reached an unsafe temperature to prevent damage to the internal components.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate.
  2. Ensure your system pressure is topped up to between 1 and 1.5 bar.
  3. Wait 15 minutes for the system to cool down and gently press the reset button.

Parts commonly replaced

  • Circulating Pump
  • Overheat Thermostat
  • Diverter Valve
Full explanation for (G) LED turning on