Check that the Direct Drain Cap is removed and that the Auto Drain Pump Cap and Auto Drain Pump Tube are installed properly. If the drain plug is installed, there is nowhere for water to drain out, and the E5 Error Code will display.
Check that you are using the original Honeywell Auto Drain Pump Tube and not an alternative. The Honeywell Auto Drain Pump Tube that comes with the product is engineered for the pump model to allow consistent water flow up to 5 meters. The diameter and length are determined scientifically. The error code may occur when water is not dispensing properly.
Check that the Auto Drain Pump Cap is securely on the Direct Drain outlet.
Make sure the Auto Drain Tube is not blocked or bent.
Make sure the filter screen on the pump is not obstructed or clogged with dirt.
Ensure the Auto Drain Pump Cap has a washer at its center.