Question

2005 Nissan Sentra got codes p1271 p1273 was wanting to know what they mean and where the sensors are located

Answer 1

P1271 = Air Fuel Ratio (A/F) Sensor 1 Circuit No Activity Detected Bank 1 = https://www.autocodes.com/p1271_nissan.html

P1273 = Air Fuel Ratio (A/F) Sensor 1 Lean Shift Monitoring Bank 1 = https://www.autocodes.com/p1273_nissan.html

Both codes are for the front Air Fuel Ratio (A/F) Sensor, which is the sensor before the catalytic converter.