[Dan Hines]

I have a 2001 Xterra and its got a P0744 code and a oil leak on the left side of the motor. Does anyone have any ideas on how to fix these problems ? Any help would be greatly appreciated,

 

[M-U-R-P-H]

Is the transmission giving any issues?
The oil leak is most likely the valve cover gasket as all of them leak eventually.

 

[JianTao]

Welcome! Valve cover gasket is a culprit. Also check your PCV system.

As far as P0744 on Nissans it's an indication of a fault in your torque converter. First thing, check the AT fluid. Idle the car until warm, then pull the transmission dipstick while it's running, in PARK. If the fluid level is correct, but brown/dark, then replace the fluid first.