Under normal circumstances, when the MACH V1 series detects that the dirty water in the dirty water tank exceeds the MAX mark, it will trigger an error that displays "Dirty Water Tank Full" on the screen. However, if the vacuum cleaner triggers the "Dirty Water Tank Full" error when the dirty water tank is not full, then it could be caused by debris on the solid-liquid separation net in the dirty water tank or on the metal contact sheet. Please refer to the following images showing these components:
 

If your vacuum cleaner is triggering the "Dirty Water Tank Full" error when the dirty water tank is not full, please try the following troubleshooting steps to verify if the issue can be resolved:

1. Confirm whether there is dirt or debris on the solid-liquid separation net in the dirty water tank. Please clean the solid-liquid separation net by rinsing it under running tap water, then install it back into the dirty water tank and check if the error persists.

2. Check whether there is water or dirt on the metal contact sheet on the dirty water tank and the corresponding metal contact sheet on the vacuum cleaner. Please clean the metal contact sheet on the dirty water tank and the metal contact sheet on the vacuum cleaner by using a clean cloth to wipe the contact sheet dry, and then check if the error persists.
3. If the error persists, please take a small piece of paper and block only the metal contact sheet on the top section of the dirty water tank (do not cover the filter with a large piece of paper) and then install the dirty water tank back into the vacuum cleaner to check if the error persists. If the error is resolved, it could be an issue caused by the dirty water tank. Please contact us with your order information for assistance.