P1138 – O2 Sensor Rich (BMW)

Description

P1138 BMW indicates the O2 sensor detects a rich mixture.

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Symptoms

  • Poor fuel economy
  • Rough idle
  • Black smoke

Causes

  • Leaking injector
  • High fuel pressure
  • Sensor fault

Diagnosis

  • Check fuel trims
  • Inspect injectors
  • Test fuel pressure

Repair

  • Replace injector
  • Repair fuel system
  • Replace sensor

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