P0131 – O2 Sensor Low Voltage (Bank 1 Sensor 1)

Description

The ECM detects a low voltage signal from the upstream O2 sensor on Bank 1.

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Symptoms

  • Rough idle
  • Hesitation
  • High fuel trims

Causes

  • Vacuum leaks
  • Faulty O2 sensor
  • Exhaust leaks

Diagnosis

  • Monitor O2 data
  • Check fuel trims
  • Inspect vacuum lines

Repair

  • Replace O2 sensor
  • Fix leaks