Display shows a steam boiler error; steam boiler does not fill or heat correctly on dual-boiler Rocket models.

Safety first: Unplug the machine and allow both boilers to cool fully. Steam boilers are under pressure and can be dangerous if opened hot.

• Check water supply and pump: Ensure the pump can deliver water (test via brew circuit). If the brew side works but the steam boiler does not fill, suspect the level probe or control board.
• Clean steam boiler level probe: Access the steam boiler top and remove the level probe. Clean the tip thoroughly to remove scale and reinstall with a new gasket if needed.
• Inspect wiring: Verify that the level probe, heating element, and temperature sensor wires are firmly connected and not heat-damaged.
• Test heating element (advanced): With a multimeter, check resistance across the steam boiler element terminals. An open circuit indicates a failed element that must be replaced.
• Control board issues: If the probe and element test good but the error persists, the dual-boiler Gicar control board may be faulty and should be replaced by a technician.