Print fail - extruder temp low

hello.

recently i have fail 2 long print sessions ( 20 hours and 14 hours )

in the first session print fail after 8 hours becouse one error make stop the print, and show message error" extruder temp too much high"

in second session ita happen the same, but in this case "extuder temp too much low"

so what can happen?? i need finish lots prints, and i need solve that problem as soon possible

- extruder cable fault

- degraded heater cartridge

- set screws at heater / thermo couple not tight