Display shows E4 and the Swan coffee maker will not start brewing; sometimes accompanied by a clicking sound.

Safety first: Unplug the coffee maker before any disassembly. Hot water and steam can cause burns.

Initial checks:

• Reseat and refill reservoir: Remove the water tank, rinse it, and ensure the bottom valve moves freely. Refill and reinstall firmly.
• Run a water-only cycle: If the machine allows, try brewing without coffee grounds to see if water flows. Listen for the pump humming.
• Descale: Run a descaling cycle to clear scale from the pump and flow meter. Scale is a common cause of E4 on pump-driven Swan models.

Advanced checks:

• Remove the side or bottom panel to access the vibration pump and flow meter.
• Check all silicone hoses for kinks or blockages. Ensure hose clamps are tight and there are no leaks.
• Inspect the flow meter (small plastic disc with two or three wires) for scale buildup. If accessible, remove and flush it with warm descaling solution.
• Test the pump by applying power briefly (only if you are trained and using proper isolation). A silent pump with correct voltage present is likely failed and must be replaced.

Note: If you are not comfortable working with mains voltage and pressurized hot water, seek professional service.