Display shows E4 and the coffee maker beeps and refuses to start brewing.

Safety first: Unplug the coffee maker before inspecting the drip-stop mechanism or switch.

Mechanical checks:

• Remove the carafe and open the filter basket. Locate the drip-stop lever or valve at the bottom of the basket area.
• Press the lever up and down manually. It should move freely and spring back. If it sticks, clean it thoroughly with warm soapy water and a soft brush to remove coffee residue.
• Inspect the carafe lid for a molded tab or protrusion that pushes the drip-stop lever when the carafe is in place. If this tab is broken, the switch may never register the carafe.

Switch inspection:

• With the unit unplugged, remove the bottom or front panel (depending on model) to access the carafe presence microswitch.
• Check that the actuator from the drip-stop lever correctly engages the switch when the lever is pressed.
• Inspect wiring for loose connectors or broken wires at the switch terminals.
• Test the switch with a multimeter: it should change from open to closed when pressed.

When to replace:

• If the switch does not change state when actuated, replace the carafe presence / drip-stop microswitch.
• If the plastic drip-stop lever or carafe lid tab is broken, replace the drip-stop assembly or carafe with lid as appropriate.

Tip: After reassembly, test the mechanism by inserting and removing the carafe while watching the lever and listening for the switch click.