Error F0 280

Safety precautions:

- If you smell gas: leave the property immediately, do not operate electrical switches, and call the gas emergency number from a safe location.

- Before any inspection, switch the boiler off at the programmer and isolate mains power at the fused spur or consumer unit. Only inspect components if you are confident and aware that internal boiler parts can be live and dangerous.

- Do not attempt to work on gas valves, ignition electrodes, or replace the burner control unit unless you are a Gas Safe registered engineer.

Initial checks a homeowner can safely do:

1) Note the exact error code and any additional flashing cause code or warning triangle. Write down what you see and when it happened.

2) Try a controlled reset: use the boiler reset button or hold the reset as described in the manual for 3 seconds. Wait to see if the fault clears and the boiler fires. If it clears and stays off for a time, arrange an engineer visit to find the root cause.

3) Check basic power and supply: make sure the boiler is getting mains power (fused spur not tripped) and that any external controls/room thermostat are calling for heat. Check the boiler pressure gauge is not showing a completely empty system (very low pressure can cause unrelated faults).

4) Check for recent work or part changes: if the boiler was recently serviced or a control module/HCM or code plug was replaced, tell the engineer—an incorrect or badly-seated module is a common cause of control errors.

Specific diagnostic and safe inspection steps (homeowner):

1) Visual external inspection: with the boiler isolated from mains, remove the outer case only if you are comfortable doing so and local safety allows. Look for signs of water ingress, corrosion, burnt components, or loose connectors at the control box. Do not touch circuit boards or connectors while power is present.

2) Check that any visible plug-in code plug / heat control module (HCM) is seated correctly. If a plug looks loose, isolate power and gently reseat it, then restore power and test. If you are unsure which module is fitted, do not force or swap parts.

3) Photograph any corrosion, burned marks, or displaced connectors and record the error code displayed—this helps the engineer.

When to call a professional and what they will do:

- Call a Gas Safe registered engineer or Worcester Bosch-authorised technician if the reset does not clear the fault, if you find water/damage or smell gas, or if any connectors appear damaged. Do not attempt replacement of the burner control unit yourself.

- A qualified engineer will carry out safe electrical checks, diagnostic tests and will read the boiler’s cause code information. They will test ignition and flame sensing circuitry, check fan and gas valve feedback, verify correct HCM/code plug compatibility, and confirm whether the burner control board or a related component (code plug, wiring, connectors, sensors or water ingress damage) must be replaced.

- If the control unit is faulty it must be replaced and correctly coded/commissioned by the engineer. The engineer will also check for secondary causes (moisture, other component failures) so the new control is not damaged.

Additional notes:

- Avoid repeatedly resetting the boiler many times; if the fault returns it likely indicates a persistent safety or electronics issue that needs professional attention.

- Provide the installer/engineer with the full error code (F0 280), any cause codes from the info menu, and any recent service history or part changes—this speeds diagnosis.

- Only let Gas Safe qualified personnel perform repairs on gas, ignition and control electronics to ensure safety and compliance.