Nissan P1148: Closed Loop Control (Bank 1) — Fix
On Nissan vehicles, P1148 means the closed-loop fuel control on bank 1 is not working — the ECM can't use the O2/A-F sensor feedback to trim the mixture.
- Applies to
- Nissan vehicles
- Est. repair cost
- $40 – $400
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include a failed A-F/O2 sensor, an exhaust leak, or a mixture fault keeping it out of closed loop. P1xxx codes are manufacturer-specific — P1148 is defined by Nissan (not part of the generic SAE J2012 set), so this definition applies to Nissan vehicles. Model years can vary, so confirm against the Nissan service manual. Fix the fault, then clear the code with a scan tool.
Symptoms
- Check engine light on
- Poor economy and emissions
- Rough running
How to fix it
- 1
Check the A-F/O2 sensor and exhaust
1. Inspect the sensor and look for exhaust leaks.
- 2
Replace the sensor
1. Replace a failed A-F/O2 sensor, then clear the code and drive a cycle.
Frequently asked questions
What is closed-loop control?
It's when the ECM trims fuel using live oxygen-sensor feedback. P1148 means bank 1 can't stay in closed loop — usually a sensor issue.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.