Boiler shows E09; may indicate communication or configuration error on some digital Elnur models.

Safety first: Isolate the boiler from the mains before accessing the control board.

• Check model configuration: Compare the DIP switch or jumper settings on the PCB with the installation manual for your exact Elnur boiler model (e.g., power rating, single/three-phase configuration).
• Verify external control wiring: Inspect connections to room thermostats, programmers, and any external control modules. Incorrect wiring can cause the PCB to detect an invalid configuration.
• Factory reset (if supported): Some Elnur digital boilers allow a factory reset via a button sequence. Follow the manual to reset parameters to default, then re-enter any required settings.
• Check PCB part number: If the PCB was recently replaced, confirm that the installed board matches the boiler model and power rating. An incompatible board can trigger E09.
• Professional reprogramming: If E09 persists, a service engineer may need to reprogram or replace the PCB.