Boiler displays E04 and stops; may indicate low water or pressure issue depending on model.

Safety first: Turn off electrical power before working on any water connections. Allow the system to cool.

• Check system pressure: If your Elnur boiler is connected to a sealed system with a pressure gauge, verify that pressure is within the recommended range (typically 1.0–1.5 bar when cold). If low, top up via the filling loop according to the installation manual.
• Bleed radiators: After topping up, bleed all radiators and any high points to remove air. Recheck and adjust pressure.
• Inspect for leaks: Look for visible leaks around radiator valves, pipe joints, and under the boiler. Any leak must be repaired before repeatedly topping up.
• Check pressure sensor/switch: Inside the boiler, locate the water pressure sensor or pressure switch. Inspect wiring and connector. If the gauge shows correct pressure but E04 persists, the sensor may be faulty.
• Reset and test: Restore power, reset the boiler, and confirm that the error clears. If the fault returns with correct pressure, arrange replacement of the pressure sensor/switch.

Warning: Do not over-pressurise the system; this can cause the safety valve to discharge.