Method for performing a self-clean cycle in a washing machine appliance

A washing machine appliance, comprising:

• a wash tub positioned within a cabinet;
• a wash basket rotatably mounted within the wash tub and defining a wash chamber configured for receiving a load of clothes;
• a water supply configured to selectively dispense wash fluid into the wash tub;
• a conductivity sensor for measuring an electrical conductivity of the wash fluid dispensed into the wash tub;
• and
• a controller operably coupled to the water supply and the conductivity sensor, the controller being configured to:
• receive a request to perform a self-clean cycle;
• supply a predetermined amount of wash fluid into the wash tub using the water supply;
• measure an initial conductivity of the predetermined amount of wash fluid in the wash tub using the conductivity sensor, the initial conductivity being measured immediately after supplying the predetermined amount of wash fluid;
• measure a final conductivity of the predetermined amount of wash fluid in the wash tub a predetermined amount of time after measuring the initial conductivity using the conductivity sensor;
• determine that the self-clean cycle is needed based at least in part on the initial conductivity and the final conductivity;
• and
• perform the self-clean cycle.