Hi Stuart, Resistance should be some ohms. Forget but think I've seen them between about 6 and 16 ohms across different makes. As suggested measure with meter, but zero ohms suggests a short, not necessarily in the sensor! I try to put a current clamp on a heater wire, so if current flows (0.5 amps approx??) you know you have voltage and continuity. Some heaters are pulsed on a duty cycle basis so a meter reading may be misleading. Regards, Nick Bell