E37 error code
E37 – Keston C90/C110 error code
What does Keston Keston C90 and C110 condensing boilers E37 mean?
Keston documents E37 for C90 and C110 boiler modules as “Return thermistor open circuit”. The manual classifies it as a module shutdown 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 E37 error code indicates keston documents E37 for C90 and C110 boiler modules as “Return thermistor open circuit”. The manual classifies it as a module shutdown 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 E37. 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 return thermistor open circuit. 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 E37 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 E37 reappears, note when it happens and give that information to the service engineer.
Reset instructions
A shutdown code requires the underlying fault to be corrected before restart. Follow the official procedure once only; repeated lockout requires a qualified engineer.
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 E37 mean?
Keston documents E37 for C90 and C110 boiler modules as “Return thermistor open circuit”. The manual classifies it as a module shutdown 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 E37 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 E37?
A shutdown code requires the underlying fault to be corrected before restart. Follow the official procedure once only; repeated lockout requires a qualified engineer.
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.