Machine displays AL4 and stops heating steam; steam boiler may have overheated or run dry.

Safety first: Turn OFF, unplug, and allow the machine to cool and depressurize fully. Open the steam wand only after pressure has dropped to zero.

• Verify water level control: Ensure the water tank is full and properly seated. On plumbed-in models, confirm inlet water pressure and open valves.
• Prime the steam boiler: With the machine cool, power ON and open the hot water tap or steam wand while activating the pump (if the model allows). Confirm that water is entering the steam boiler (you should hear filling and see water/steam from the wand).
• Reset safety thermostat: Locate the steam boiler and find the manual-reset thermostat (if fitted). Press the reset button gently. If it clicks, it had tripped.
• Inspect level probe: Identify the steam boiler level probe (a metal rod entering the top of the boiler with a single insulated wire). Remove and clean the probe with a non-abrasive pad to remove scale. Do not shorten or bend the probe.
• Test operation: Reassemble, power ON, and monitor filling and heating. If AL4 recurs, the steam boiler thermostat, level probe, or control board may be defective and require professional diagnosis.