the probe uses different metal in each wire the wires are twisted together in the probe, it will read low ohms , if the twisted part is damaged it will still read low ohms but can not generate enough power to read accurate use a heat gun to check if off use the chart stated above to check the probe if the reading matches the gun the gauge is bad you can buy a gun for $80 and use it on trips to check wheel bearings , tires rear end , and transfer case