P2273 — O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2

P2273: O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2 — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • The check-engine warning may illuminate if the downstream bank 2 oxygen-sensor signal remains biased rich.
  • Fuel economy may decrease and engine response may become sluggish.
  • Sometimes the engine feels normal despite the recorded fault.

Possible causes

  • A faulty post-catalyst oxygen sensor at bank 2 sensor 2.
  • Damaged signal wiring or a loose, corroded sensor connector.
  • An actual rich-running condition, such as a leaking injector or incorrect airflow measurement, can also influence the sensor signal.

What to check

  • Read P2273 with other stored codes; identify the downstream oxygen sensor on bank 2.
  • Inspect the plug and wiring for corrosion, damage and intermittent contact.
  • Examine live sensor data to distinguish a signal stuck rich from a confirmed rich air-fuel mixture.
  • If wiring is sound, check for evidence of excess fuel and evaluate the sensor using the vehicle's specified procedure.

Also written as: P2273-00, P227300 (some scan tools add the fault-type byte, e.g. -00).