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P2251 Powertrain

O2 Sensor Negative Current Control Circuit (Bank 1 Sensor 1)

The negative current control line (Vs−) of the wide-band lambda sensor on bank 1 sensor 1 is open or out of range. Used as the virtual ground reference for the Nernst cell.

Affected components

  • Oxygen sensor wideband
  • Oxygen sensor wiring

Common causes

  • High likelihood: Vs− line open
  • Medium likelihood: Wide-band sensor failed

Possible symptoms

  • Check engine light on
  • Increased fuel consumption
  • Possible rough idle or hesitation
  • Failed emissions test

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions
  • A drive cycle may be required after repair

Related codes

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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