Display shows E4 and the dishwasher stops; often occurs during filling or early in the cycle, sometimes accompanied by water in the base tray.

Safety first: Disconnect the appliance from mains power. Water may be present in the base; be cautious of sharp metal edges and hot components.

• Inspect base tray: Remove the front lower panel or side panel to access the base. If water is present, carefully sponge or vacuum it out. Locate the anti-flood float switch and ensure it moves freely.
• Find the leak source: With the base dry, run a short fill test while observing the machine (power restored). Look for drips from the wash pump seals, boiler connections, tank gaskets, door gasket, or hoses.
• Check inlet valve: If water continues to enter the tank even when the machine is off, the water inlet solenoid valve is stuck open and must be replaced.
• Inspect overflow pipe and standpipe: Ensure the overflow tube in the tank is correctly seated and not cracked. A missing or misfitted overflow can cause water to spill into the base.
• Test float switch: With power off, disconnect the float switch and test continuity while moving the float. Replace the switch if it does not change state reliably.
• Reset error: After fixing the leak and drying the base, clear the E4 error by cycling power and run several test cycles to confirm no further leakage.