New PCV & 4 O2 sensors; ECM clear 3 different ways why is 2004 Nissan Maxima 3.5 SES 1273?

Question

Three Months ago just as it was being inspected, my 2004 Nissan Maxima 3.5 lit up a service engine soon (SES) light which read as p1800 VIAS Solenoid and p0037 o2 sensor 2 bank 1 and those were replaced and cleared the ECM. after 30 miles the SES lit up with new codes C1130 crank sensors, p0726 TPI and engine speed sensors and 1273 O2 sensor 1 bank 1 and with all intent to order everything, I went out and read the codes again and only the 1273 code remained so I replaced all the remaining bank 2 O2 sensors as well as the pain in the butt sensor 1 bank 1 between the engine and fire wall and did so with a special open socket for the job so it is properly seated and is not cracked. while I was there I replaced the PCV valve and filters as such were indicated as a possible problem. I then did separate ECM clearing-- gas pedal code--disconnect battery for two hours with terminals touching-- and MAF code and Actron Reader to erase codes in ECM. I inspected for vacume, intake, and exaust manifold leaks and cooling fluid/oil mixings and all is good. I even traced the wires looking for evidence of wire failure or corrosion and again all looks good.Two months later this car is still SES-ing a 1273. With all new OEM O2 sensors, new PCV, codes cleared 3 different ways, and o2 Heat&Mon OK why is my 2004 nissan maxima 3.5 is still SES-ing 1273 ?

Answer 1

P1273 A/F Sensor

Nissan has a TSB about this code condition it may just apply to your condition.  TSB # 05-095 . What this TSB is about is inspecting for a loose or missing catalytic heat shield

Answer 2

P1273 NISSAN Code - Air Fuel Ratio Sensor 1 Bank 1 Lean Shift Monitoring
Read more: https://www.autocodes.com/p1273_nissan.html