P1172 – Fuel Trim Rich (Bank 1, Nissan)

Description

The ECM detected an excessively rich fuel mixture on Bank 1.

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Symptoms

  • Poor fuel economy
  • Black smoke
  • Rough idle
  • Fuel smell
  • Check engine light

Causes

  • Leaking injector
  • Faulty O2 sensor
  • High fuel pressure
  • MAF sensor fault
  • ECM control issue

Diagnosis

  • Check fuel trims
  • Inspect injectors
  • Test fuel pressure
  • Scan live data

Repair

  • Repair injector
  • Replace O2 sensor
  • Fix fuel pressure issue
  • Clean MAF sensor

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