b65 error code
b65 – Keston C90/C110 error code
What does Keston Keston C90 and C110 condensing boilers b65 mean?
Keston documents b65 for C90 and C110 boiler modules as “Waiting for the fan to start; the fan may be stuck”. The manual classifies it as a recoverable blocking code; b-codes can delay operation and retry, while E-codes shut the affected module down.
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 Keston C90 and C110 condensing boilers b65 error code indicates keston documents b65 for C90 and C110 boiler modules as “Waiting for the fan to start; the fan may be stuck”. The manual classifies it as a recoverable blocking code; b-codes can delay operation and retry, while E-codes shut the affected module down. 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
The affected boiler-module display alternates or shows b65. Heat output from that module may be delayed, restricted or shut down, although the second module may behave differently.
Common causes
The module control detected waiting for the fan to start; the fan may be stuck. Possible causes depend on the code and include system pressure or circulation, excessive temperature, fan operation, ignition or flame proving, a thermistor circuit, gas-valve connection, thermal protection or internal electronics.
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
Record b65 and identify which C90/C110 module display shows it. Do not remove the cabinet; the documented cause requires qualified internal diagnosis.
Can you fix this error code yourself?
The safest next step depends on the exact model and the cause behind the code. External checks may help, but a returning fault needs professional diagnosis.
A successful reset is not proof that the underlying issue is fixed. If b65 reappears, note when it happens and give that information to the service engineer.
Reset instructions
The module may attempt to fire again automatically. Do not repeatedly power-cycle it; if the blocking code persists or recurs, arrange qualified diagnosis.
Applicable products and models
Keston C90 and C110 condensing boilersC90; C1102003 product generationWhen to contact a professional
Contact a suitably qualified Gas Safe registered engineer and provide the exact module display and code. Internal inspection, testing and replacement parts must be handled professionally.
Frequently asked questions
What does Keston Keston C90 and C110 condensing boilers b65 mean?
Keston documents b65 for C90 and C110 boiler modules as “Waiting for the fan to start; the fan may be stuck”. The manual classifies it as a recoverable blocking code; b-codes can delay operation and retry, while E-codes shut the affected module down.
Can I fix Keston Keston C90 and C110 condensing boilers b65 myself?
Some external checks may be suitable for the user, but the result depends on the exact model and cause. Use the official manual and arrange service if the code returns.
Should I reset the product after code b65?
The module may attempt to fire again automatically. Do not repeatedly power-cycle it; if the blocking code persists or recurs, arrange qualified diagnosis.
When should I arrange a repair?
Contact a suitably qualified Gas Safe registered engineer and provide the exact module display and code. Internal inspection, testing and replacement parts must be handled professionally.