Here is some similar posts and their fix -
It would seem that you have either a bad air/fuel ratio sensor or you have an exhaust leak near the sensor or catalytic area.
2004 Nissan Maxima 3.5L, USA/Canada
Customer Concern: Code P1273. Changed the mass air flow sensor. The light is still on.
Tests/Procedures: 1. Review the 3 Technical Service Bulletins that pertain to code P1273.
2. Check for exhaust manifold/ Catalytic Converter cracks near the Air/Fuel Ratio Sensor
Potential Causes: Air Fuel Ratio (AFR) Sensor
Air-Fuel Ratio Sensor
Cracked Catalytic Converter
Cracked Exhaust Manifold
Tech Tips: P1273 is for Bank one Air/Fuel Ratio Sensor (firewall side). Indicates a the Air/Fuel Ratio Sensor has shifted to lean for too long.
Diagnostic Codes: P1273
Author: Steve Wilson
Average Reported Mileage: 94000
Confirmed Fix Summary
Confirmed Fix 1 - Air Fuel Ratio (AFR) Sensor, Spark Plug(s)
1 - Catalytic Converter
1 - Exhaust Manifold
Confirmed Fix Details
Tech Reported Fix Details Confirmed Fix
March 10, 2008 2004 Infiniti G35, 3.5L, USA/Canada *
Replaced Air Fuel Ratio (AFR) Sensor
Replaced Spark Plug(s)
- Random misfire code 300.Bank one running lean.Swicth air fuel ratio sensors side to side .Lean running fallowed the sensor.Replace the bad sensor and car is now 100%.Replaced plugs and checked coils on a scope and found nothing wrong. Air Fuel Ratio (AFR) Sensor, Spark Plug(s)
October 12, 2009 2005 Nissan Quest, 3.5L *
Replaced Catalytic Converter
- heat shield spot welds on the convertor were leaking. heat shield was barely held on. Catalytic Converter
January 31, 2008 2004 Nissan Maxima, 3.5L, USA/Canada
94,000 miles Exhaust Manifold