System and method for detecting an elevated drain for a washing machine appliance

A washing machine appliance comprising:

• a sump for collecting wash fluid;
• a supply valve for providing the wash fluid into the sump;
• a drain assembly comprising a drain hose that fluidly couples the sump to an external drain for discharging the wash fluid through the external drain;
• a water level detection system comprising a pressure sensor fluidly coupled to the sump;
• and
• a controller operably coupled to the supply valve, the drain assembly, and the water level detection system, the controller being configured to:
• measure a sump pressure using the water level detection system;
• operate the supply valve to provide a first volume of the wash fluid into the sump such that the sump pressure reaches a target pressure;
• operate the drain assembly to drain the wash fluid from the sump;
• operate the supply valve to provide a second volume of the wash fluid into the sump such that the sump pressure reaches the target pressure;
• determine that the external drain is elevated based at least in part on a difference between the first volume and the second volume;
• and
• adjust at least one operating parameter of the washing machine appliance in response to determining that the external drain is elevated, wherein adjusting the at least one operating parameter of the washing machine appliance comprises decreasing a fill volume of a subsequent fill cycle to compensate for residual wash fluid that fails to discharge from the drain hose.