i would personally just replace it, but it can be tested, ill presume your using fiesta turbo management, at 0 degrees C, it should read 88000-102000 ohms, at 80 deg C, 3000-4500 ohms, this is measured with plug disconnected across the 2 pins, with the plug connected, ignition on & at 0 deg C, you should measure 3.8 volts approx, & at 80 deg C, 0.7 approx these readings are off autodata so sorry if there wrong