trouble codes please help?

[versa071979]

pulled these codes with my obd2 scanner today any help would be great to help me fix this issue my car is an 2001 nissan path le 3.5 the manufactured dade is 7/01 im not sure if its an 01 or 01.5 here are the codes as they came up on my my scanner. I did the scan this morning while the car was cold with an outside temp of 39 f

p0138 g mil
o2 sensor circuit high voltage

p0139 g
02 sensor circuit
slow responcse

p0160 g
02 sensor circuit no activity detected

p0138 g pend
02 sensor circuit high voltage

[versa071979]

also forgot to mention there is a small leak in the exhaust somewere i can hear it dont know if that would effect anything

[Towncivilian]

You have a 2001.5 Pathfinder.

Replace the passenger's side post-cat (downstream) oxygen sensor with this Bosch direct-fit sensor from Advance Auto Parts. Bosch is the manufacturer for the OEM sensor. Order online and use discount code VISA and pick-up in store to get the sensor for $53 before tax. You'll need a 22mm or 7/8" oxygen sensor socket for replacement. That should take care of the P0138 and P0139 codes. P0160 is the driver's side post-cat (downstream) sensor. Use this sensor as a replacement - order as a separate order with the same coupon code the day after you buy the first one to get it for $50 before tax.