Installing Universal Oxygen Sensor

[Mao]

I just purchased a Bosch universal O2 sensor with a four wire application. On wire is black, one gray and two are white.
Does anyone know if it matters which white wire is spliced into which?
The instructions just say match the colored wires.

[Mao]

In case anyone wants to know ... I found out that it does not matter as long as white is to white ....no polarity.