I purchased a new O2 Sensor for my 2001 Honda Accord and I cannot understand why it has a female plug and not a male plug as the existing one has so I assume I have to move the wires from the new unit to the old plug.
However, the old plug has 2 black, a white and a green wire and the new unit has 2 black a white and a blue wire.
Can I just connect the new wires to the old plug placing the blue wire where the green was?
Yes, it is possible.
The two black wires are probably the heater wires and you need to figure out signal polarity on the remaining two wires.
See Do I have to rely on wire color to correctly wire up an O2 sensor? for detailed steps on how to do this.
Before splicing in the new sensor, just make sure that the new sensor fits in the existing bung hole. This can be an issue if the new sensor is of the generic, model-agnostic variety.
and welcome to the forum.
You have to be very careful with these, but in this case yes, the Blue goes to Green. It would have been better if the parts supplier gave you the correct one to start with!
Here's a note from Denso, the main Japanese manufacturer of those sensors. If you read the chart, you'll see the green listed under 'old OEM sensor' and the blue under 'new Denso sensor' Link to PDF from Denso
