The 4 prong sensor is actually 2 sensors in one case .
As Az explained , the diagonally opposed pins will get a resistance reading for each sensor, but because both sensors have the same values and declining resistance/temp curves , the plug can be installed in any of the 4 positions and it will always be correct, circuit wise.. [ providing each sensors thermistor is good]
That is why there is no orientation key/tab...
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