How much does it cost to fix P0131 on a Toyota?

Repair costs for P0131 on Toyota vehicles typically range from $100 to $350 depending on the underlying cause. The most common fix is: A worn-out or contaminated upstream (Bank 1 Sensor 1) oxygen sensor no longer producing a proper voltage signal..

Toyota Check Engine Code

P0131 on Toyota

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

Severity: medium DIY difficulty: 2/5 Toyota cost: $100–$350

Last updated April 30, 2026 Also covers: Lexus, Scion

P0131 on Toyota: what makes it different

Toyota's Bank 1 Sensor 1 (upstream) oxygen sensor is a heavily used component that reports fuel trim data to the ECU, and on high-mileage 1.8L and 2.4L four-cylinder engines it commonly degrades to the point of reporting an abnormally low voltage signal.

Most-affected engines

2ZR-FE 1.8L (Corolla)
2AZ-FE 2.4L (Camry, RAV4)
1AZ-FE 2.0L (older Camry, Avensis)

Common model years: 2005–2015

Most likely cause on Toyota

A worn-out or contaminated upstream (Bank 1 Sensor 1) oxygen sensor no longer producing a proper voltage signal.

Known Toyota engine-family issues

Toyota's four-cylinder engines (2ZR-FE, 2AZ-FE) are known for upstream O2 sensors that slowly degrade rather than fail outright, so drivers often notice a gradual drop in fuel economy before the code appears.

Toyota-specific causes (most common first)

Aged/worn upstream O2 sensor (very common past 100,000 miles on Toyota four-cylinders)
Oxygen sensor connector corrosion or a loose pin at the ECU harness
Exhaust leak upstream of the sensor causing false lean readings
Sensor contamination from oil consumption or coolant leaks into the exhaust
Wiring harness rubbing/chafing near the exhaust manifold heat shield
Failing fuel injector causing a persistently lean condition that mimics sensor failure

Toyota-specific diagnostic tip

Use live sensor data to watch the Bank 1 Sensor 1 voltage — a healthy Toyota upstream O2 sensor should swing actively between roughly 0.1V and 0.9V at idle. If it's flatlined near zero or barely moving, the sensor itself is the likely culprit rather than a wiring fault.

Symptoms drivers report

Check engine light
Rough idle or hesitation
Reduced fuel economy
Possible hesitation under load

Typical repair cost on Toyota

Most Toyota owners fix P0131 for between $100 and $350, depending on which underlying cause turns out to be at fault. Start with the most-likely cause for your vehicle — A worn-out or contaminated upstream (Bank 1 Sensor 1) oxygen sensor no longer producing a proper voltage signal. — before throwing parts at it.

Toyota P0131 FAQ

Do I need the exact Toyota OEM oxygen sensor for this fix?

Toyota's ECU is fairly tolerant of quality aftermarket sensors, but many owners report the most reliable long-term results with an OEM or OEM-equivalent sensor, especially for Bank 1 Sensor 1.

Will P0131 hurt my Toyota's fuel economy?

Yes, a failing upstream O2 sensor often causes the ECU to run a slightly richer fuel mixture, which can noticeably reduce MPG until it's replaced.

Can a simple exhaust leak cause this code on my Toyota?

Yes — an exhaust leak near the manifold before the sensor lets in extra oxygen, which can trick the sensor into reporting a false lean signal that looks like P0131.