HeatCore C1 Error Code Reference
The HeatCore C1 displays status and error codes on its front panel. The table below lists all codes you may encounter, what they mean, what you can do as a homeowner, and whether a Gas Safe registered engineer is required.
Error codes
| Code | Description | Homeowner Action | Engineer? |
|---|---|---|---|
| EA | No ignition — boiler failed to light after multiple attempts | Check gas supply is on, check prepayment meter has credit, thaw condensate pipe if frozen, press reset and wait 30 seconds | Yes, if persists after 3 resets |
| E2 | Flame loss during operation — burner lit but flame was lost unexpectedly | Press reset, check gas supply to the property, ensure no draughts near the flue terminal | Yes, if persists |
| E9 | Overheating — the boiler has exceeded its safe operating temperature | Let the boiler cool for 30 minutes, check that all radiator valves are open (closed valves restrict water flow and cause overheating), press reset | Yes, if persists |
| F1 | Low water pressure — system pressure has dropped below the minimum threshold | Repressurise the system using the filling loop to 1.0–1.5 bar | Only if pressure keeps dropping |
| F3 | Fan fault — the combustion fan has not reached the required speed | Press reset and allow the boiler to attempt a restart | Yes |
| F7 | Flame detected after shutdown — the boiler is detecting a flame signal when no flame should be present | Turn the boiler off at the isolation switch immediately and call a Gas Safe registered engineer | Yes — urgent |
| A7 | DHW (domestic hot water) temperature sensor fault — the sensor reading is out of range | Hot water temperature may be erratic or unavailable; heating may still function normally | Yes |
| C6 | Fan speed deviation — the fan is running but not at the expected speed | May cause intermittent lockouts; press reset to clear | Yes |
| d3 | Burner control unit fault — the electronic control board has detected an internal error | Press reset; if the code clears, monitor for recurrence | Yes, if persists |
Normal status indicators
The following symbols appear during normal operation and do not indicate a fault:
| Symbol | Meaning | Action |
|---|---|---|
| H | Standby — the boiler is on and ready but not currently firing | No action needed |
| = | Central heating active — the boiler is firing to heat the radiators | No action needed |
| ≈ | Hot water active — the boiler is firing to heat domestic hot water | No action needed |
Important: If you see error code F7 (flame detected after shutdown), do not attempt to reset the boiler. Turn it off at the isolation switch and contact a Gas Safe registered engineer immediately. This code indicates a potential safety issue that requires professional inspection before the boiler is operated again.
Before calling an engineer
Note down the exact error code displayed, the time it appeared, and what the boiler was doing when the fault occurred (heating, hot water, or standby). This information helps the engineer diagnose the issue more quickly. You can also photograph the display for reference.