Boiler shows E9 or low-pressure symbol; boiler does not start

Safety: Allow the system to cool before topping up. Do not over-pressurise the boiler.

• Check pressure gauge: If below 1.0 bar (cold), top up using the integrated or external filling loop according to the Junkers manual until the needle is in the green zone.
• Bleed radiators: After topping up, bleed radiators to remove air and recheck pressure, topping up again if necessary.
• Inspect for leaks: Look for visible water around radiators, valves, and under the boiler. Repair leaks before repeated topping up.
• Pressure sensor: If pressure is correct but the error persists, a technician should test and replace the pressure sensor if faulty.