Check engine light

[cvpi71]

Hi folks
my 98 Infiniti I30 has 111k miles recently I get the Check engine light, I got the Code reader and pulled the code it's p0135, what do I need to do to make it go away. The O2's were replaced at 90k miles before I acquire the car. I am running out of option , what and where is bank 1? I cleared the codes and only to find it on couple of weeks later.
(P0135 Heated O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1))

[Nahkapohjola]

V6 engine cylinder arrangemen is like the V. First \ 3 cylinders Bank1, next / 3 cylinders: Bank2... Both have their own exhaust manifold, O2 sensor(s)

Points to low voltage, harness/connector problems. Maybe bad O2 sensor? Check http://www.cardomain.com/ride/748507/14
Check charge voltage, att batt AND at ECU.

[rather_b_boatin]

I've seen new O2 sensors go after only 3 months and 3K miles. Definatly check connections first.