Lockout 5 flashes error code
Lockout 5 flashes — Fan-speed failure
What does Keston Celsius 25 and 25P boilers Lockout 5 flashes mean?
Five red lockout flashes every two seconds indicate that fan speed has fallen below the required operating threshold.
The code identifies the condition detected by the product; it does not always identify the failed component on its own. Confirm the full code and exact model before ordering parts or attempting a reset.
The Keston Celsius 25 and 25P boilers Lockout 5 flashes error code indicates five red lockout flashes every two seconds indicate that fan speed has fallen below the required operating threshold. This guide explains what the code means, the symptoms and likely causes, the checks that are safe to make, and when to stop and arrange an authorised repair.
Symptoms you may notice
Red lockout LED flashes five times every two seconds; fan or ignition sequence may fail; boiler remains locked out.
Common causes
Fan failure; fan PCB fault; loose or damaged fan connections; wiring or control-board fault.
Before you start troubleshooting
Use the display, rating label or product menu to confirm the exact model. Similar-looking codes can have different meanings across product generations and regions.
- Record the complete code before switching the equipment off.
- Check only user-accessible controls, filters and external connections described in the manual.
- Do not open gas, refrigerant, combustion or electrical compartments.
Troubleshooting steps
Switch the boiler off and arrange professional diagnosis. The fan, its PCB, wiring and control signals are internal components and must not be tested by the user.
Can you fix this error code yourself?
This fault is not intended for user repair. Do not remove covers or test internal components; record the code and contact an authorised technician.
A successful reset is not proof that the underlying issue is fixed. If Lockout 5 flashes reappears, note when it happens and give that information to the service engineer.
Reset instructions
Only reset after the underlying condition has been checked. Where the official manual permits a reset, turn the boiler user-control knob off, wait, then turn it on again. Do not repeatedly reset a returning lockout.
Applicable products and models
Celsius 25 and 25P boilersCelsius 25; Celsius 25PLegacyWhen to contact a professional
Contact a Gas Safe registered engineer if the pattern returns, the boiler will not reset, there is evidence of overheating or leakage, or any check requires access inside the appliance.
Frequently asked questions
What does Keston Celsius 25 and 25P boilers Lockout 5 flashes mean?
Five red lockout flashes every two seconds indicate that fan speed has fallen below the required operating threshold.
Can I fix Keston Celsius 25 and 25P boilers Lockout 5 flashes myself?
This code is not classed as user-fixable. Record it and arrange authorised diagnosis rather than opening the product.
Should I reset the product after code Lockout 5 flashes?
Only reset after the underlying condition has been checked. Where the official manual permits a reset, turn the boiler user-control knob off, wait, then turn it on again. Do not repeatedly reset a returning lockout.
When should I arrange a repair?
Contact a Gas Safe registered engineer if the pattern returns, the boiler will not reset, there is evidence of overheating or leakage, or any check requires access inside the appliance.