Using NPN transistor as Thermistor emulator
simulate this circuit &ndash; Schematic created using CircuitLab

If desired thermistor resistance is Rt then R3 = RtR4/(Rt-R4). For Rt = 2K -> R3 = 2.5k.

A small error will be due Q1 Vce_sat of 2mV for R1 = 1k or 3mV for R1 = 10k