P1273 — Air/Fuel (A/F) Sensor 1 (Bank 1) Lean Shift / Lean Mixture
CAUTIONIs it safe to drive? Drive gently and get it looked at soon — it can worsen or fail inspection.
What P1273 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P1273 means on specific makes
Nissan / Infiniti CAUTION
The front A/F sensor on Bank 1 is reporting a persistent lean condition the ECM can't correct. Source lists it as 'Heated oxygen sensor (HO2S) bank 1 - lean mixture.' Often a worn A/F sensor or a real lean cause (leak).
- Worn front A/F sensor ($100-300)
- Intake/vacuum leak
- Low fuel pressure / dirty injectors
- Exhaust leak ahead of sensor
Check first: Check for intake leaks and fuel pressure, then the A/F sensor itself. P1274 is the rich-mixture counterpart.
Source: troublecodes.net/nissancodes, ricksfreeautorepairadvice.com/nissan-obd2-codes