Code P0841, where is the transmission fluid pressure sensor/ switch “a” circuit range/performance?

This can be the transmission is low on fluid, or the pressure pump has gone out FYI. We can try the sensor first. This is a CVT unit which is known to go out.

Transmission Fluid Pressure Sensor-Switch “A” - Circuit Range/Performance trouble code.

The sensor is inside the control valve. If the fluid is burnt, then the transmission will need a rebuild which is common for these. Check out the images (below). Let us know how it goes.

Can the sensor be replaced or does the control valve need to be replaced?

I also found a small leak on one of the side of the oil pan. The transmission fluid was also recently changed like 3 months ago. Would it be possible its throwing a code because it’s low on transmission oil?

Also do you have a photo of the sensor or know where they sell the Sensor?

Yes, it can be low fluid causing the code. I would make sure the unit is full and then clear the codes. Yes the control valve will nee to be replaced because the sensor is inside of it. You will need to pump fluid into the overflow plug and allow it to run our with the engine running. Here is a guide to help and images below to help you.

Type .................... Genuine NISSAN CVT Fluid NS-3

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

Check out the images (below). Let us know how it goes