P1148 — Closed Loop Control Function (Bank 1) Inoperative
CAUTIONIs it safe to drive? Drive gently and get it looked at soon — it can worsen or fail inspection.
What P1148 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P1148 means on specific makes
Nissan / Infiniti CAUTION
The ECM can't maintain closed-loop fuel control on Bank 1 — it isn't getting usable feedback from the front A/F (air-fuel ratio) sensor, so it stays in open loop and fuels by table. Common Nissan code tied to the front A/F sensor.
- Failed front A/F ratio sensor, Bank 1 ($100-300)
- A/F sensor heater/wiring fault
- Exhaust leak skewing readings
- Vacuum/intake leak
Check first: Check the front A/F sensor signal and heater; a dead or lazy front A/F sensor is the usual fix. Often pairs with P1273/P1278.
Source: troublecodes.net/p1codes/p1148, autocodes.com/p1148_nissan.html