How do I fix P0031for a NISSAN Altima 2002 2.5 l

Question

where are A/F sensors and how do I can replace this ?

Answer 1

On your 2002 Nissan Altima the P0031 is for the "Front Oxygen (O2) Sensor)" The sensor is on the front of the engine, between the radiator and the engine.

More Information: http://nissanhelp.com/diy/altima/projects/2002_2003_nissan_altima_o2_sensor_location_25_engine.php