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P0043 Powertrain

HO2S Heater Control Circuit Low Bank 1 Sensor 3

Heater control voltage of the bank 1, sensor 3 oxygen sensor is below the expected range — short to ground or low-resistance fault.

Affected components

  • Oxygen sensor b1s3 heater
  • Heater wiring

Common causes

  • High likelihood: Heater wiring shorted to ground
  • Low likelihood: Connector pins corroded - high contact resistance
  • Low likelihood: Harness chafing through insulation

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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