P1143 – Lambda Sensor Internal Fault (BMW)

Description

P1143 BMW indicates an internal electrical or mechanical fault in the lambda sensor.

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Symptoms

  • Rough idle
  • Hesitation
  • Reduced power

Causes

  • Sensor failure
  • Internal short
  • Connector issue

Diagnosis

  • Check sensor resistance
  • Inspect connector
  • Scan DME

Repair

  • Replace sensor
  • Clean connector
  • Repair wiring