Drain hose not looped up above sink drain allowing wash water to syphon from the dishwasher.
The manufacturer has assigned this error or fault code to indicate that when the drain pump is running it is not experiencing the back pressure it expects. This is usually an indication that there is a water leak in the drain system. Check all hoses and connections. Check under the dishwasher for any major leak. If all checks out, be certain there is a proper loop in the drain hose to prevent siphoning. Finally, if the problem persists, the drain pump itself might be defective.