P0131Medium urgency

O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)

Emission · Oxygen Sensors

⚠️ Safe to drive — fuel economy and emissions affected.

What this means

The upstream O2 sensor on Bank 1 is reading abnormally low voltage, indicating a consistently lean mixture or a faulty sensor. The ECU may incorrectly adjust fuel trims based on this bad reading.

Likely causes

Failed upstream O2 sensorMost common
Exhaust leak near O2 sensorCommon
Lean fuel condition (check P0171)Common

Estimated repair cost

O2 sensor replacement$150 – $350

Exhaust leak repair$100 – $400

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Frequently asked questions

What does P0131 mean?

The upstream O2 sensor on Bank 1 is reading abnormally low voltage, indicating a consistently lean mixture or a faulty sensor. The ECU may incorrectly adjust fuel trims based on this bad reading.

Is P0131 serious?

Safe to drive — fuel economy and emissions affected.

How much does it cost to fix P0131?

Repair costs for P0131 range from $150 – $350 depending on the root cause and your vehicle.

Can I drive with P0131?

You can drive short distances but should have it repaired within 1-2 weeks to prevent further damage.