P0131: Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 1)

What does the P0131 error code mean?

The P0131 diagnostic trouble code or error code reads "Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 1)." This code appears when the engine control module detects a low voltage signal from the oxygen sensor located in Bank 1 of the engine (the side of the engine with cylinder 1) and Sensor 1, which is found upstream of the catalytic converter. On a typical V6 or V8 engine, this is the cylinder bank on the driver’s side of the engine. This sensor monitors the oxygen levels of your car’s exhaust gases to help the engine control module adjust the air-fuel mixture for optimal combustion.

The importance of addressing P0131

A malfunctioning oxygen sensor can disrupt the engine's air-fuel balance, leading to decreased fuel efficiency, increased emissions, reduced vehicle performance, and potential damage to the catalytic converter. Eventually, it can also result in costly repairs. An incorrect air-fuel mixture, or air-fuel ratio, can cause the engine to run poorly or overheat.

Can I safely drive my car with error code P0131?

Driving with the P0131 code is possible but not recommended because the failing sensor will typically get worse over time. The engine could run inefficiently, which will lead to higher fuel consumption, and prolonged use while running an unoptimized air-fuel ratio can lead to engine damage. Your best bet is to only drive the vehicle to the repair shop, or better yet, have the vehicle towed there, especially if it is misfiring, as the misfire will accelerate engine damage.

Common symptoms of P0131

• Illuminated check engine

• Poor fuel economy

• Rough idling

• Decreased engine performance, like hesitation on acceleration

• A strong exhaust smell

• Possible engine misfires, indicated by shaking, loss of power under acceleration, or rough idling

Diagnosing P0131

Diagnosing the P0131 error involves the following steps:

• Scan for codes: Use an OBD-II scanner to confirm the P0131 code and check for related codes.

• Inspect the oxygen sensor: Check for damage, contamination or loose connections in the Bank 1, Sensor 1 oxygen sensor.

• Test the sensor voltage: Measure the sensor's voltage output to ensure it falls within the expected range.

• Check for exhaust leaks: Inspect the exhaust system near the sensor for leaks that could affect readings.

• Evaluate wiring and connectors: Look for damaged or corroded wiring in the sensor circuit.

• Monitor live data: Use a scanner to observe oxygen sensor voltage and the engine control module's fuel trim adjustments during engine operation.

Repairing P0131

Repairing the P0131 code typically involves:

• Replacing the Bank 1, Sensor 1 oxygen sensor if it is faulty.

• Repairing or replacing damaged wiring or connectors in the sensor circuit.

• Fixing any exhaust leaks near the sensor.

• Addressing engine issues, like vacuum leaks or incorrect fuel pressure, that may affect the air-fuel balance.

• Clearing the code and performing a test drive to confirm the repair’s effectiveness.

Related reading

Follow the link below to reach our diagnostic check engine trouble codes catalog:
On-board diagnostics (OBD-II) trouble code directory