Error FD 231

Safety precautions: do not open the boiler casing or attempt repairs to gas or internal electrical components. Only perform non-intrusive visual checks and simple resets. If you smell gas, leave the property immediately and call the gas emergency number. If you see signs of electrical damage (burn marks, melting, repeated trips) isolate the boiler at the consumer unit and call a qualified electrician and Gas Safe engineer.

Initial checks homeowners can do:

1) Note the exact display: write down FD 231 and any cause code shown in the information menu (press the spanner/return button if your model shows a cause code). Also note the date/time and any recent events (power cut, lightning, meter work, building works).

2) Check whether the whole house lost power or only the boiler: test lights and other sockets. If multiple circuits were affected, this points to a mains/supply issue rather than the boiler itself.

3) Check your consumer unit (fuse box) for tripped MCBs or RCDs and reset any tripped devices in line with standard electrical safety practice. If a breaker trips straight away after reset, leave it off and call an electrician.

4) Check the boiler isolator/fused spur (usually a switch adjacent to the boiler) is on and the fused spur fuse is intact. Do not remove covers or fuses inside the boiler.

5) Check external controls: room thermostat, programmer, timers, and any wireless relay. If an external control has lost power or is set to isolate the boiler, restore or reset it.

Specific diagnostic and fix steps (homeowner-level):

1) Attempt a single controlled reset: Follow your boiler’s manual method—either press the reset button for about 3 seconds or turn the dial to the reset position and hold for 3 seconds. Only try one reset. If the boiler clears the code and runs, monitor it for recurrence.

2) If the boiler does not reset or FD 231 returns immediately: confirm mains supply to the property is stable and no breakers are tripping. If other appliances are affected or breakers repeatedly trip, contact a qualified electrician.

3) If mains supply is stable but FD 231 persists: check any external fused spur feeding the boiler (the external switch/fuse) for a blown fuse and replace only the external fuse if you are competent to do so. If unsure, stop and call an electrician or Gas Safe engineer.

4) If you have a display or information menu, check for additional cause codes and any pattern (for example other fault codes alongside FD 231). Make a note of all codes to give to the engineer.

5) If the boiler runs after reset but you experienced a recent mains disturbance (power cut, lightning, electrician work), keep an eye on it. If the fault reappears more than once, do not keep resetting—this can mask an underlying fault.

When to call a professional: Contact a Gas Safe registered engineer if FD 231 persists after a single reset, if the consumer unit shows repeated tripping, if you suspect internal electrical damage, or if any other fault codes appear. A qualified electrician should be called for confirmed mains issues or repeated trips at the consumer unit. Provide the engineer with the boiler model, serial number, the FD 231 code and any cause code, the times the fault occurred, and details of any recent power events to speed diagnosis.

Important warnings: do not attempt to access or repair the boiler’s internal electronics, gas valve, burner, wiring or PCB yourself. Working on gas and mains electricity is dangerous and illegal for unqualified persons. The FD 231 is often a simple reset after a power interruption, but recurring faults require professional inspection to ensure safe and reliable operation.