When the system detects a fault, an alphanumeric code appears on the display: No flame detected Check gas supply pressure and ignition electrodes. Exhaust gas blockage Check the flue/chimney for obstructions or intake issues. Water overheating Let the unit cool down and restart. Inlet temp sensor fault Check the sensor connections. Electronic board error
The manual highlights several "Error Codes" that may appear on the screen: : Generally relate to temperature sensor issues. junkers hydronext 5600 s manual