Display shows E04 and brewing stops; sometimes accompanied by water leaking into the drip tray instead of the cup.

Safety first: Unplug the coffee maker before removing the brew group or drip tray.

• Remove and clean brew group: Open the service door, remove the brew group assembly, and rinse it thoroughly under lukewarm water. Pay attention to the filter screen and moving joints. Let it dry completely.
• Check for obstructions: Inspect the brew chamber area inside the machine for loose coffee grounds, paper, or foreign objects that could block movement.
• Lubricate moving parts: Apply a small amount of food-grade silicone grease to the brew group rails and piston seals if recommended in the Grundig manual.
• Reset position: With the brew group removed, plug in the machine and power it on. Let it complete its self-test (you may hear the motor run). Then power off, unplug, reinstall the brew group, and test again.
• Service if error persists: If E04 reappears, the brew group position sensor or drive motor/gearbox may be faulty and require professional replacement.