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P0156 Powertrain

O2 Sensor Circuit Malfunction (Bank 2, Sensor 2)

Same condition as P0136 but on the downstream sensor of bank 2. The catalyst efficiency monitor for bank 2 cannot run while this fault is active.

Affected components

  • Oxygen sensor downstream

Common causes

  • High likelihood: Downstream sensor aged

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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