P1123 – Mixture Too Lean (Bank 1) (BMW)

Description

P1123 BMW indicates the mixture is too lean on Bank 1.

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Symptoms

  • Rough idle
  • Hesitation
  • High fuel trims

Causes

  • Vacuum leak
  • MAF contamination
  • Weak fuel pump

Diagnosis

  • Check fuel trims
  • Inspect vacuum lines
  • Test fuel pressure

Repair

  • Fix vacuum leaks
  • Clean MAF
  • Repair fuel system

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