Error 228 V

Safety first: If you smell gas, leave the property immediately and call the gas emergency number. If the boiler has a fault light or shows a lockout, do not try to repeatedly force it to run. Any work on gas, ignition components, or internal wiring must be carried out only by a Gas Safe qualified engineer.

Initial basic checks a homeowner can do (no internal access):

1) Note and record exactly when the fault appears (hot water, heating, after reset, intermittent) and take a photo of the display including any cause code in the information menu. This helps engineers and warranty support.

2) Try a single simple reset: press and hold the boiler reset button or follow the manual reset method for 3 seconds. If the boiler runs after reset but the fault returns, do not continue resetting repeatedly — that is a sign an engineer is required.

3) Check that the gas supply to the property is on and other gas appliances work. If multiple appliances have no gas, contact your gas supplier. Do not attempt internal gas isolation work yourself.

4) Check for obvious external issues: signs of water ingress around the boiler casing, evidence of rodents chewing cables, or heavy condensation that could affect wiring. Photograph and note anything suspicious.

If you are competent, comfortable and understand you must isolate power and gas before opening the casing (note: internal work is generally not recommended for homeowners):

5) Isolate electrical supply at the fused spur and the gas supply to the boiler before removing the front panel. If you are unsure how to do this safely do not proceed — call Gas Safe.

6) With the boiler isolated and panel removed, visually inspect the ionisation/ignition cable from the electrode to its connector. Look for cracks, chafing, burn marks, corrosion, oil/condensate contamination or signs of moisture. Also check the electrode itself for heavy soot, damage or displacement. Do not bend or reposition the electrode significantly or attempt gap adjustment unless you are qualified.

7) Inspect connectors and wiring to the burner control/PCB for loose plugs, corrosion or water ingress. A loose or corroded connection can create false signals. If you find a loose connector, note its position and condition and do not attempt improvised repairs; a Gas Safe engineer should reseat and test connectors and wiring.

8) If the boiler environment is damp or there is water on the PCB/connector area, mention this to the engineer — moisture can cause false ionisation signals.

9) Do not attempt to replace the ionisation electrode, ignition lead, air/gas ratio valve or the burner control unit yourself unless you are a Gas Safe registered engineer. These components affect safe ignition and gas delivery and require calibration and testing.

What a qualified engineer will do (what to expect when you call):

10) The engineer will run controlled diagnostic tests with appropriate instruments, read stored cause codes from the information menu, check burner sequence and verify if the ionisation electrode and cable are producing a correct flame signal only when flame is present.

11) They will check the integrity of the ignition/flame sensing circuit, earth/ground continuity, and review the air/gas ratio control valve and modulating gas valve feedback. If an ionisation cable or electrode is faulty, they will replace it and test. If the air/gas ratio valve or the burner control (PCB) is at fault, they will replace and calibrate those parts as required.

12) After parts replacement or repair, the engineer will run the boiler through start/stop cycles, measure flame stability and CO/CO2 if needed, and confirm there are no further false signals before leaving the job.

When to call Worcester Bosch or your installer/warranty support: If the boiler is under warranty, contact Worcester Bosch or your installer before arranging independent repairs. Give them the fault code (228 V), the cause codes from the information menu if shown, a description of when it happens, how often, and any photos you took.

Final note and recommendation: Do not carry on using the boiler if the fault recurs. Flame sensing and gas control are safety-critical systems — always use a Gas Safe registered engineer to diagnose and repair this fault. If the fault is intermittent and the boiler repeatedly locks out after reset, arrange service promptly to avoid loss of heating or hot water and to ensure safe operation.