Kwiksen Heated 2Pcs O2 Oxygen Sensor 1 Sensor 2 Upstream Left/Right Replacement 234-4308 5S4523 2003-2004

I replaced all 4 02 sensors with Kwiksen 02 Sensors.My vehicle is not going into OL and stays in CL on bank one sensor 1 and 2 after one month and only 3 hundreds miles after installing these in my 03 Infiniti G35 sedan.I believe the issue is the heater element or just a bad sensor.I paid for and ordered a Kwiksen replacement for bank 1 and I am sure they will send me a good replacement however this is a very difficult tight area to work on in this vehicle.They look like They are made good however they are far from GOOD.I will in the future replace all 4 sensors once again with Bosch or some other brand I can trust because I no longer have faith in Kwiksen 02 Sensors and that is a shame because when they are working they do feel fine in the car.