A method of predicting failure of an applicator (48, 50) of a hot melt liquid dispensing system (10, 220), the applicator (48, 50) configured to dispense hot melt liquid and the hot melt liquid dispensing system (10, 220) further having a hot melt liquid heater, associated with the applicator (48, 50), the method comprising: providing a plurality of applicator parameter values (314, 324) of a first operating parameter of the applicator (48, 50), each applicator parameter value (314, 324) of the plurality of applicator parameter values (314, 324) being temporally associated with a time interval of a first block of time; characterized in that the method further comprises: determining a first subset of applicator parameter values (314, 324) of the plurality of applicator parameter values (314, 324), each applicator parameter value (314, 324) of the first subset of applicator parameter values (314, 324) indicating no dispensing activity of the applicator (48, 50) for a temporally associated time interval of the first block of time; determining a second subset of applicator parameter values (314, 324) of the plurality of applicator parameter values (314, 324), each applicator parameter value (314, 324) of the second subset of applicator parameter values (314, 324) indicating dispensing activity of the applicator (48, 50) for a temporally associated time interval of the first block of time; and based on the first subset of applicator parameter values (314, 324) and the second subset of applicator parameter values (314, 324), determining a predicted time of failure of the applicator (48, 50). providing a plurality of applicator parameter values (314, 324) of a first operating parameter of the applicator (48, 50), each applicator parameter value (314, 324) of the plurality of applicator parameter values (314, 324) being temporally associated with a time interval of a first block of time; characterized in that the method further comprises: determining a first subset of applicator parameter values (314, 324) of the plurality of applicator parameter values (314, 324), each applicator parameter value (314, 324) of the first subset of applicator parameter values (314, 324) indicating no dispensing activity of the applicator (48, 50) for a temporally associated time interval of the first block of time; determining a second subset of applicator parameter values (314, 324) of the plurality of applicator parameter values (314, 324), each applicator parameter value (314, 324) of the second subset of applicator parameter values (314, 324) indicating dispensing activity of the applicator (48, 50) for a temporally associated time interval of the first block of time; and based on the first subset of applicator parameter values (314, 324) and the second subset of applicator parameter values (314, 324), determining a predicted time of failure of the applicator (48, 50). determining a first subset of applicator parameter values (314, 324) of the plurality of applicator parameter values (314, 324), each applicator parameter value (314, 324) of the first subset of applicator parameter values (314, 324) indicating no dispensing activity of the applicator (48, 50) for a temporally associated time interval of the first block of time; determining a second subset of applicator parameter values (314, 324) of the plurality of applicator parameter values (314, 324), each applicator parameter value (314, 324) of the second subset of applicator parameter values (314, 324) indicating dispensing activity of the applicator (48, 50) for a temporally associated time interval of the first block of time; and based on the first subset of applicator parameter values (314, 324) and the second subset of applicator parameter values (314, 324), determining a predicted time of failure of the applicator (48, 50).