Worcester Bosch — EA, E9, F9
EA is a flame-loss fault — usually a dirty flame sensor, gas supply issue or ignition electrode. E9 signals overheating from a stuck pump, sludge or blocked heat exchanger. F9 points to a control board fault and typically needs a PCB replacement.
Vaillant — F22, F28, F75
F22 means low water content — check pressure and top up the filling loop. F28 is an ignition failure, often caused by a low gas supply, faulty gas valve or spark electrode. F75 is a pump/pressure sensor fault common on ecoTEC models — a Gas Safe fix.
Ideal — F1, F2, L2
F1 is low pressure — repressurise to 1.2 bar. F2 signals no flame detection (gas supply, valve or electrode). L2 on older Logic models is an ignition lockout requiring engineer diagnosis.
Baxi — E133, E168, E125
E133 is a gas supply / ignition fault. E168 is a general fault — often PCB or sensor. E125 signals poor water circulation, usually a stuck pump or airlock.
Should I reset the boiler?
Most boilers allow two or three resets before locking out. If the same code returns after a reset, stop and call a Gas Safe engineer — repeated resets can worsen underlying faults.
Boiler flashing a fault code? Call for same-day diagnosis in KT/TW.
Call 07932 898534Frequently asked questions
Where do I find my boiler's fault code list?
Every boiler manual has a table of fault codes. If you don't have the paper copy, search the manufacturer's website for your model number (usually on a sticker under the front panel).
Can I fix a fault code myself?
Low-pressure codes can be cleared by topping up the filling loop. Everything else — flame loss, ignition, sensor or PCB codes — requires a Gas Safe registered engineer by law.
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