Trouble codes › P0131

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

Oxygen sensors

P0131 means bank 1's front oxygen sensor is stuck at low voltage (lean), from a failed sensor, wiring or a real lean condition.

The front oxygen sensor on bank 1 is staying at low voltage, which normally means a lean mixture. The engine computer decided it's stuck low: either the engine really is lean or the sensor or wiring is faulty.

Can I keep driving? Yes, but get it fixed soon.

Usually drivable, but get it checked soon; a real lean condition can lead to misfires.

Common causes

  1. A failed oxygen sensor
  2. A short to ground in the signal wire
  3. An exhaust leak near the sensor pulling in air
  4. A real lean condition (vacuum leak, low fuel pressure)

Symptoms

  • Check-engine light
  • Hesitation or rough idle
  • Worse fuel economy

What to check first

  1. Check for lean codes (P0171) and exhaust leaks first.
  2. Inspect the wiring for damage.
  3. Watch the sensor with a scan tool; snapping the throttle open should drive it high (rich).
  4. Replace the sensor if it won't respond.

What does P0131 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P0131

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Related codes

General guidance for P0131 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.