Dishwasher shows E21, water may not drain properly or pump runs loudly.

Safety first: Unplug the dishwasher and be prepared for water spillage when opening the sump.

• 1. Clean filters: Remove and clean the coarse and fine filters. Check for food debris in the sump.
• 2. Access drain pump from inside: In many Constructa models, a small cover in the sump can be removed to access the drain pump impeller. Remove the cover and check for glass, bones, or other obstructions. Rotate the impeller gently to ensure it moves freely.
• 3. Check drain hose and sink trap: Detach the drain hose from the sink siphon and inspect for blockages. Clean the siphon connection.
• 4. Test drain: Reassemble, restore power, and run a drain-only or cancel program to see if water is pumped out correctly.

When to call a technician: If the pump hums but does not turn, or is completely silent, it may need replacement.