E4 error appears and brewing stops; sometimes accompanied by water leaking into the drip tray instead of the cup.

Safety first: Disconnect from mains and allow pressure to dissipate for at least 15 minutes before opening any water circuit.

Steps to clear blockage:

• Clean brew head and outlet: Remove the portafilter or brew group (depending on model). Clean the metal shower screen and outlet channels with a brush and descaling solution. Ensure all holes are free of coffee oils and residue.
• Run descaling cycle: Reassemble and run a full descaling program using Gorenje-approved descaler. This helps clear internal scale that can cause overpressure.
• Check overpressure valve: Locate the overpressure valve near the pump or thermoblock. Inspect for scale buildup or stuck plunger. If removable, soak in descaler and rinse thoroughly.
• Assess pump performance: If the pump is very loud but little water flows, or it vibrates without pushing water, it may be failing. Check for airlocks by priming: fill the tank, run a hot water cycle without coffee, and tilt the machine slightly to help air escape.

When to replace parts: If E4 persists after cleaning and descaling, the pump or overpressure valve may need replacement. Use a compatible ULKA pump and Gorenje-specified valve for your model.