E77 error code
E77 – Solar panel sensor open circuit
What does Keston Keston Qudos 28h and Qudos 28hP heat-only boilers E77 mean?
Keston documents E77 for the Qudos 28h and Qudos 28hP as “Solar panel sensor open circuit”. Match the code to this exact product generation because Keston code meanings vary between boiler 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 Qudos 28h and Qudos 28hP heat-only boilers E77 error code indicates keston documents E77 for the Qudos 28h and Qudos 28hP as “Solar panel sensor open circuit”. Match the code to this exact product generation because Keston code meanings vary between boiler 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 boiler display flashes E77 and may enter lockout or stop normal burner operation until the detected condition is corrected.
Common causes
The official fault table associates E77 with solar panel sensor open circuit. The underlying cause may be the named sensor, wiring, supply, circulation, fan, combustion or control 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 relevant sensor, connector, wiring continuity and controller input; replace only with the approved component.
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 E77 reappears, note when it happens and give that information to the service engineer.
Reset instructions
After correcting the cause, press the fascia Reset button once. Power-cycling alone does not clear a Qudos lockout; do not repeatedly reset a returning fault.
Applicable products and models
Keston Qudos 28h and Qudos 28hP heat-only boilersQudos 28h; Qudos 28hP2007–2011 manual generationWhen to contact a professional
Contact a suitably qualified Gas Safe registered engineer when the code persists, returns after one permitted reset, requires a service reset, or involves internal testing or component replacement.
Frequently asked questions
What does Keston Keston Qudos 28h and Qudos 28hP heat-only boilers E77 mean?
Keston documents E77 for the Qudos 28h and Qudos 28hP as “Solar panel sensor open circuit”. Match the code to this exact product generation because Keston code meanings vary between boiler controllers.
Can I fix Keston Keston Qudos 28h and Qudos 28hP heat-only boilers E77 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 E77?
After correcting the cause, press the fascia Reset button once. Power-cycling alone does not clear a Qudos 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, returns after one permitted reset, requires a service reset, or involves internal testing or component replacement.