Bosch Dishwasher Error Code E:3400

E:3400 means the dishwasher's flow sensor is detecting water movement through the inlet system without the control board having activated the filling valve. This indicates that water is entering the machine outside of a normal, commanded fill cycle. The most common source is a filling valve that is stuck open or failing to seal properly when it should be closed.

It is not advisable to continue running the dishwasher with E:3400 present. An uncontrolled water inlet can lead to overfilling, which may trigger the anti-flood float switch and could result in water leaking onto the floor or into the cabinet below. Power the unit off at the circuit breaker if you notice standing water or continuous water intake and address the fault before running another cycle.

Repair costs vary depending on which component has failed. A replacement filling valve typically costs between $20 and $60 for the part, with labor adding $80 to $150 if a technician performs the work. If the control board's relay or the entire board requires replacement, total costs can range from $150 to $350 or more depending on the specific board and local labor rates.

A knowledgeable DIYer can start by inspecting the filling valve for visible debris, checking the wiring harness for damage, and confirming whether water enters the tub while the dishwasher is in standby. Replacing the filling valve is a moderately accessible repair on most Bosch models. However, if the fault points to a control board relay failure, professional diagnosis and repair are recommended to avoid damaging the board or other components.

A reset may clear the displayed code temporarily, but if the underlying cause, such as a stuck filling valve or a shorted wiring circuit, is still present, the error will return. Resetting is useful for confirming whether the fault is intermittent, but it is not a repair. The filling valve and its actuation circuit must be diagnosed and corrected to resolve the error permanently.