Error F0 280

Safety precautions:

1) If you are not comfortable working with electrical or gas appliances do not proceed—call a Gas Safe engineer. Electrical and gas isolation are required before opening the boiler casing. Risk of electric shock, gas leakage or voiding warranty if incorrect repairs are attempted.

2) Always turn the boiler off at the mains isolator and, if possible, isolate the gas supply before removing any covers. Wait a few minutes for capacitors to discharge.

3) If you see water inside the boiler, signs of burning, smell gas or see damaged wiring, do not touch—turn off the appliance at the mains, ventilate the area and call a professional.

Initial homeowner checks you can do (no tools or minimal tools):

1) Record the exact error code, any accompanying triangle or flashing light pattern and take a photo of the display. Note recent events (power cut, storms, work nearby, freezing temperatures, water leaks).

2) Try a basic reset: press the boiler reset/spanner/return button as per the user manual or switch the boiler off at the mains for 60 seconds then switch back on. Check whether the F0 280 returns immediately or after restart.

3) Check boiler mains supply and fused spur: make sure the isolator is on and the fused connection unit or consumer unit fuse hasn’t tripped. Check other household appliances to confirm mains power is stable.

4) Check system water pressure on the gauge—if pressure is very low or the boiler has recently lost pressure this can cause other faults; repressurise only if you know how and it is safe to do so.

5) Look for obvious signs of damage or water ingress around the boiler casing, wiring looms and the flue. Smell for burnt electronics. Photograph any damage.

If you are comfortable with basic safe access and only if the boiler is isolated from the mains (and you are competent), limited further checks:

1) Isolate the boiler at the mains isolator and, if possible, at the fused spur. Wait a few minutes.

2) Remove the outer casing following the manufacturer instructions. Locate the control PCB and the Heat Control Module (HCM) / code plug assembly—this is typically a small plug-in module on the control board.

3) Inspect the HCM and PCB connectors for corrosion, loose pins, bent pins, moisture, or burn marks. If connectors appear wet, corroded or burnt, do not attempt to run the boiler and contact an engineer.

4) If connectors look intact and you are confident, carefully unplug and re-seat the HCM/code plug and any obvious multi-pin connectors. Ensure the module is fully seated and locked into place. Refit the cover, restore mains and try a reset.

5) If reseating clears the fault, run the boiler and monitor for reoccurrence. If the fault returns, do not attempt further electrical repairs.

Diagnostic and next-step guidance for an engineer (what to provide/get done):

1) Provide the engineer/manufacturer with the exact error code (F0 280), any secondary codes, the model and serial number, photos, and the actions you have already taken (reset, reseat HCM, power cycle). This speeds diagnosis.

2) The engineer will check harness continuity, supply voltages to the PCB and HCM, sensor inputs and the integrity of the connectors. They will use service menus/quick info to read logged fault history and run built-in tests (fan, pump, ignition sequence) to isolate the control fault.

3) If the HCM is proven faulty or not recognised, the HCM (code plug) may be replaced or reprogrammed. If the control box / PCB is at fault it will need replacing. Both are specialist tasks and will require a competent engineer to handle safe isolation, component replacement, calibration and gas safety checks.

4) If water ingress, corrosion, or burn damage is present the underlying cause (leaks, condensation, etc.) must also be fixed to prevent repeat failures.

Final note and professional help:

1) F0 280 is not a routine DIY repair—replacing or repairing the control box or HCM involves live electrical work and affects gas safety. Call a Gas Safe registered engineer or Worcester Bosch service. If the boiler is under warranty, contact Worcester Bosch support before any parts are replaced to avoid voiding warranty.

2) When calling, give the engineer the fault code, model/serial, what you tried (reset, reseat), and any photos. This helps get the correct parts and quicker resolution.

3) If the boiler is left without heat or hot water and the fault prevents operation, seek prompt professional assistance rather than attempting further unprotected repairs.