BoilerFaultCodesWorcester Bosch 228 V Fault Code
Also written as 228V — same fault.
The Worcester Bosch 228 V fault code means: your boiler thinks it can see a flame even though it hasn't started the ignition process yet, which prevents it from running for safety reasons.. It appears on 3 Worcester Bosch models in our database.
Technical description: Flame signal without flame present – air/gas ratio control valve may need replacing as might the ionisation cable
What causes the Worcester Bosch 228 V fault?
This fault occurs when the boiler's internal sensor detects an electrical signal signifying a flame at a time when the burner should be off. The most common reason is a faulty detection electrode sending a false signal or a gas valve that is leaking slightly, allowing a small amount of fuel to stay lit. Because the boiler cannot safely confirm the fire is out, it shuts down to prevent any risk of overheating or gas build-up.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Worcester Bosch models that show the 228 V fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 228 V fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026