P1148 – Closed Loop Control (Bank 1, Nissan)

Description

The ECM detected improper closed-loop fuel control on Bank 1.

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Symptoms

  • Poor fuel economy
  • Rough idle
  • Hesitation
  • Rich or lean mixture
  • Check engine light

Causes

  • Faulty O2 sensor
  • Fuel pressure issue
  • Vacuum leak
  • Injector problem
  • ECM control fault

Diagnosis

  • Check fuel trims
  • Inspect O2 sensor
  • Test fuel pressure
  • Scan live data

Repair

  • Replace O2 sensor
  • Repair vacuum leaks
  • Fix fuel pressure issues
  • Service injectors

Related Problems

Related Fault Codes