Question

Where can I locate the P0138 & P0139 O2 sensors on my 1999 Nissan Maxima 3.0L?

Answer 1

Hi there,

This code is for the rear O2 sensor, this is the one in the exhaust pipe behind the catalytic converter under the car.

Answer 2

P0138 NISSAN - HO2S12 Circuit High Voltage
Read more: https://www.autocodes.com/p0138_nissan.html

P0139 NISSAN - HO2S12 Slow Response
Read more: https://www.autocodes.com/p0139_nissan.html