Program stops with E04; sometimes accompanied by poor spray performance or unusual spray arm behavior.

Safety: Switch off power and water supply before disassembling any components.

E04 is often related to the water distribution system and spray pressure.

• Clean spray arms: Remove upper and lower spray arms by unscrewing or unclipping them. Rinse under running water and use a toothpick to clear blocked jets. Refit securely.
• Check filters: Remove the bottom filter assembly and coarse filter. Clean thoroughly under hot water to ensure good flow.
• Inspect heat exchanger (if fitted): On many Neff models, the left side houses a heat exchanger and water distributor. Remove the left side panel and inspect for heavy limescale or debris. Flush the channels with warm water and descaler if necessary.
• Diverter valve: Listen during operation: if you hear repeated clicking and E04 appears, the diverter valve or its sensor may be faulty. Inspect the water distributor / diverter valve assembly for stuck mechanisms or broken gears.
• Replace faulty parts: If cleaning does not resolve the issue, replace the spray arms if damaged, or the Neff water distributor / diverter valve assembly if it does not move correctly.

After reassembly, run a hot cycle with dishwasher cleaner to clear remaining residues.