DHW Thermistor Fault error code
DHW Thermistor Fault – Keston Combi² error message
What does Keston Keston Combi² C30 and C35 combination boilers DHW Thermistor Fault mean?
Keston documents “DHW Thermistor Fault” on the Combi² C30 and C35 as domestic-hot-water temperature sensor or circuit fault. This is the 2023 Combi² generation and must remain separate from the earlier Combi C30/C35 range.
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 Combi² C30 and C35 combination boilers DHW Thermistor Fault error code indicates keston documents “DHW Thermistor Fault” on the Combi² C30 and C35 as domestic-hot-water temperature sensor or circuit fault. This is the 2023 Combi² generation and must remain separate from the earlier Combi C30/C35 range. 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 boiler display shows DHW Thermistor Fault. Central heating, domestic hot water or both may stop, lock out or operate abnormally until the detected condition is resolved.
Common causes
Domestic-hot-water temperature sensor or circuit fault. The exact cause may involve system pressure or circulation, a sensor, fan, pump, flame-proving circuit, gas supply, mains supply, thermostat communication or boiler-control configuration.
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 the exact “DHW Thermistor Fault” message and the conditions when it appeared. Do not remove the casing; follow the official display instruction and arrange qualified diagnosis where directed.
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 DHW Thermistor Fault reappears, note when it happens and give that information to the service engineer.
Reset instructions
Use Restart once only when the official fault screen offers it and after the permitted external checks. If DHW Thermistor Fault returns, stop resetting and arrange professional diagnosis.
Applicable products and models
Keston Combi² C30 and C35 combination boilersCombi² C30; Combi² C352023 product generationWhen to contact a professional
Contact Keston while the appliance is under warranty, or a suitably qualified Gas Safe registered engineer (RGII in Ireland), when the message persists or returns or when internal testing or repair is required.
Frequently asked questions
What does Keston Keston Combi² C30 and C35 combination boilers DHW Thermistor Fault mean?
Keston documents “DHW Thermistor Fault” on the Combi² C30 and C35 as domestic-hot-water temperature sensor or circuit fault. This is the 2023 Combi² generation and must remain separate from the earlier Combi C30/C35 range.
Can I fix Keston Keston Combi² C30 and C35 combination boilers DHW Thermistor Fault 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 DHW Thermistor Fault?
Use Restart once only when the official fault screen offers it and after the permitted external checks. If DHW Thermistor Fault returns, stop resetting and arrange professional diagnosis.
When should I arrange a repair?
Contact Keston while the appliance is under warranty, or a suitably qualified Gas Safe registered engineer (RGII in Ireland), when the message persists or returns or when internal testing or repair is required.