E11 error code
E11 – Flow/return sensor calibration test failed
What does Keston Keston C36 and C36P Combi boilers E11 mean?
Keston documents E11 for the C36 and C36P Combi as “Flow/return sensor calibration test failed”. Match this code to the exact product because identical E-codes can have different meanings on other Keston controllers.
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 C36 and C36P Combi boilers E11 error code indicates keston documents E11 for the C36 and C36P Combi as “Flow/return sensor calibration test failed”. Match this code to the exact product because identical E-codes can have different meanings on other Keston controllers. 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 display flashes E11 and the boiler enters lockout or suspends normal heating and hot-water operation.
Common causes
The official service table associates E11 with flow/return sensor calibration test failed, involving the corresponding sensor, pressure, supply, communication, controller, fan, valve, ignition, flame, combustion, flue or circulation circuit.
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
A qualified engineer should inspect the named sensor, its location, connector, wiring and controller reading.
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 E11 reappears, note when it happens and give that information to the service engineer.
Reset instructions
After the cause has been corrected, press Reset once. Turning the power off and on does not clear this controller’s lockout; do not repeatedly reset a returning fault.
Applicable products and models
Keston C36 and C36P Combi boilersC36 Combi; C36P Combi2004–2011 manual generationWhen to contact a professional
Contact a suitably qualified Gas Safe registered engineer when the code persists or returns, or when diagnosis requires internal measurements, wiring checks or replacement parts.
Frequently asked questions
What does Keston Keston C36 and C36P Combi boilers E11 mean?
Keston documents E11 for the C36 and C36P Combi as “Flow/return sensor calibration test failed”. Match this code to the exact product because identical E-codes can have different meanings on other Keston controllers.
Can I fix Keston Keston C36 and C36P Combi boilers E11 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 E11?
After the cause has been corrected, press Reset once. Turning the power off and on does not clear this controller’s lockout; do not repeatedly reset a returning fault.
When should I arrange a repair?
Contact a suitably qualified Gas Safe registered engineer when the code persists or returns, or when diagnosis requires internal measurements, wiring checks or replacement parts.