Baxi E104 means the boiler has detected a faulty Safety Assist printed circuit board (PCB). That is Baxi’s current public error-code description. A PCB is an electronic control board, but E104 should not be used as a shopping list or a reason to open the boiler.
The safe response is to confirm the exact model and code, try only the reset permitted by its user guide, and arrange a repair if E104 remains or returns.
What does Baxi fault code E104 mean?
Baxi lists E104 as “faulty Safety Assist PCB”. The code relates to the electronic board associated with the appliance’s Safety Assist function.
Even with that specific wording, an engineer should confirm the fault before replacing a board. Baxi’s own glossary explains that a boiler PCB controls the appliance electronically and may shut the boiler down because another component is not working correctly. The connected system must be checked rather than assuming a new PCB is automatically required.
Which Baxi boilers use E104?
The current Baxi error-code table places E104 within a group covering ranges including Platinum Compact, Duo-tec Compact, Megaflo Compact, 600, 800, Assure, Platinum, Platinum+, Duo-tec, Megaflo and EcoBlue products, as well as related Main and Potterton appliances.
Codes and control arrangements can vary by model. Find the complete model name and consult its official user guide. Record any other symbols or codes shown with E104.
What can you safely check?
- Check that the boiler display has stable power.
- Note whether a recent property power cut or interruption occurred.
- Record whether heating, hot water or both stopped.
- Photograph E104 and the model details.
- Use one model-approved reset if the correct manual allows it.
If the code clears, monitor the appliance. If it returns, do not keep cycling the power or repeatedly pressing reset.
Can I repair or replace the PCB?
No. Do not remove the boiler casing, unplug the board, reseat connectors, probe voltages, bridge terminals or fit a replacement. Boiler electronics work with combustion and safety controls, and internal access belongs with a Gas Safe registered engineer.
Where a part is required, it must be correct for the exact boiler and installed and configured appropriately. Similar-looking boards are not necessarily interchangeable.
Could E104 be caused by a power cut?
A recent power interruption is useful information to give the engineer, but it does not change Baxi’s code definition. A single model-approved reset may clear a temporary condition. A persistent or recurring E104 needs inspection.
A household electrician can address an obvious property supply problem, but the boiler’s internal electronics remain gas-appliance work.
Is E104 dangerous?
The boiler has reported a fault involving a named safety system and may stop operation. Leave that protection in place. Do not bypass controls or try to force the appliance to run.
If you smell gas, suspect a leak, or a carbon-monoxide alarm sounds, avoid electrical switches, leave the property and call the National Gas Emergency Service on 0800 111 999 from a safe place.
Does E104 mean the boiler must be replaced?
No. An electronic control fault can be repairable. Whether repair or replacement makes sense depends on the confirmed fault, boiler age and condition, parts availability and the value of the repair—not on E104 alone.
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Baxi E104: the short answer
E104 is Baxi’s code for a faulty Safety Assist PCB. Confirm the exact model, keep the casing closed and use only the permitted reset. If the code remains or returns, arrange a Gas Safe registered repair.