CENTRAL HEATING
SCOTLAND

No flame detected — ignition failed

Check gas supply is on at the meter; reset the boiler. If it recurs, call an engineer — could be ignition lead, gas valve, or flame sensor.

Safety thermostat tripped — overheating

The primary circuit has overheated. Check pressure is 1.0–1.5 bar and radiators aren't all closed. If it persists, the pump or heat exchanger may be blocked.

Hot water demand active (not a fault)

D1 is a status code, not an error — it means the boiler is heating hot water. No action needed.

Flow/return thermistor fault

Temperature sensor is reading incorrectly. Replace thermistor — common quick fix.

Flue sensor trip / condensate blocked

Check the condensate pipe isn't frozen or blocked, especially in winter. Clear any ice, reset. If it recurs, the flue sensor needs replacing.

Low water pressure

Repressurise using the filling loop to 1.0–1.5 bar, then reset. This is DIY-safe — your manual shows the filling loop.

Flame loss during operation

Check gas supply on. If fine, the flame sensor or gas valve may be faulty — book an engineer.

Ignition lockout — failed to light

First check the gas supply and reset. If it locks out again, an engineer is needed — ignition components or blocked flue.

System pre-fill needed

Boiler needs repressurising at the filling loop. Fill to 1.2 bar then reset.

Reset required

The boiler has recorded a fault that needs a manual reset — press the reset button for 3 seconds.

Low system pressure

Pressure below 0.6 bar. Recharge via the filling loop to 1.0–1.5 bar, then reset — your manual shows how.

Ignition attempt failed

Check gas is on and reset. If it persists, the ignition board, gas valve, or spark electrode needs an engineer.

Flame went out while running

Could be a gas pressure drop or flue blockage. Check the gas meter, reset, and call if it recurs.

Flow/return sensor fault or low pressure

First check pressure is 1.0–1.5 bar and top up if needed. If the sensor is the cause, it's a common replacement.

Low water pressure

Top up the system via the filling loop to 1.2 bar, then reset — DIY-safe, see your manual.

Overheat thermostat tripped

The system has overheated. Check pressure and that all radiators are open. If it recurs, the pump may be failing.

Hot water thermistor fault

Temperature sensor on the DHW side needs replacing — book an engineer.

Flame signal lost

Check gas supply and reset. Recurring E119 usually needs a new flame sensing electrode or gas valve.

System fault — wiring/sensor

Often a wiring harness or PCB fault. Call us — this needs diagnostics.

Ignition failure / no flame

Check gas is on and reset. If it returns, the ignition electrode or gas valve is likely the fault.

Overheat thermostat

Check pressure and air in radiators. If it persists, pump or heat exchanger issue.

Flame loss during operation

Gas pressure drop or flue problem. Reset and call if it comes back.

Flow sensor defect

Sensor needs replacing — fairly common Glow-worm fix.