Code P0043 is an error code for Heated oxygen sensor #3. This applies to California emissions equipped Rogue's only. Federal and Canada emissions do not have this '3rd' Oxygen Sensor.
Here is the excerpt from the Service Manual:
Code: P0043
Description: Heated oxygen sensor 3 heater control circuit low
DTC detecting conditon:The current amperage in the heated oxygen sensor 3 heater circuit is out of the normal range. (An excessively low voltage signal is sent to ECMthrough the heated oxygen sensor 3 heater.)
Possible Cause:• Harness or connectors(The heated oxygen sensor 3 heatercircuit is open or shorted.)• Heated oxygen sensor 3 heater
You can refer to the manuals here:
http://www.nicoclub.com/FSM/Rogue/