Thermostat displays E05 and heating does not start; the control module reports no boiler flame signal or fails to energize the boiler relay.

Safety: This involves mains and boiler control wiring. Isolate power at the main switch or breaker before touching any wiring. If you are not experienced with heating controls, contact a professional.

• Verify power off: Turn off the boiler and Ngenic control module at the isolation switch and confirm the display is off.
• Inspect wiring: Remove the cover of the Ngenic boiler interface module and check that the call-for-heat wires are firmly secured in the correct terminals as per the Ngenic installation manual and boiler wiring diagram.
• Check boiler settings: Ensure the boiler is set to accept external thermostat control (e.g., room stat terminals enabled, not bridged).
• Restore power and test: Turn power back on, set the thermostat to a high temperature, and listen for the relay click in the Ngenic control module and boiler ignition.

If E05 persists and no relay click is heard, the relay on the Ngenic boiler interface module may be defective and the module should be replaced by a qualified technician.