P0130: O2 sensor circuit malfunction (bank 1) sensor 1

The engine computer gets no usable signal from an oxygen sensor: the signal is missing, doesn’t change, or doesn’t make sense. Without it, the engine computer can’t correct the fuel mixture as precisely, or check the catalytic converter.

Updated 16 October 2026

What P0130 means

Oxygen sensors measure how much oxygen is left in the exhaust. Sensor 1 sits in front of the catalytic converter and tells the engine computer whether the mixture burnt rich or lean, so it can correct the fuel. Sensor 2 sits behind the converter and is used mainly to check that the converter works. Some cars have a sensor 3 further down.

Bank 1 is the side of the engine with cylinder 1; only V and flat engines have a bank 2. P0130 means the engine computer has found a fault in the circuit of bank 1, sensor 1: its signal is missing, implausible or doesn’t behave as expected.

Many petrol cars use a sensor whose voltage swings between about 0.1 and 0.9 volts as the mixture changes; others use a wide-band sensor with a different kind of signal. The service information for your car says which type it has.

P0131 to P0166: low, high or no activity, and the other sensors

The codes follow the same pattern for each sensor: “circuit” (a fault in the circuit), “low voltage”, “high voltage” and “no activity” (the signal doesn’t change). Low voltage reads as a lean mixture and high voltage as a rich one, so a mixture that really is lean or rich can set them, as well as a faulty sensor or wiring. Look at the other codes and the fuel trims before replacing the sensor.

Faults on sensor 2 or 3, behind the catalytic converter, rarely change how the car drives, but the catalytic converter can’t be checked until they’re fixed. Slow-response codes, such as P0133 and P0139, and heater codes, such as P0135 and P0141, are explained on their own pages.

• P0131: O2 sensor circuit low voltage (bank 1) sensor 1

  An oxygen sensor’s voltage stays too low, which, on the common type of sensor, reads as a lean mixture (too much oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is lean.

  Common causes: faulty oxygen sensor, signal wire shorted to earth, or a damaged connector, exhaust leak in front of the sensor, vacuum leak or low fuel pressure making the mixture lean.

• P0132: O2 sensor circuit high voltage (bank 1) sensor 1

  An oxygen sensor’s voltage stays too high, which, on the common type of sensor, reads as a rich mixture (too little oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is rich.

  Common causes: faulty or contaminated oxygen sensor, signal wire shorted to a voltage, or a damaged connector, leaking injector or fuel pressure too high, making the mixture rich.

• P0134: O2 sensor circuit no activity detected (bank 1) sensor 1

• P0136: O2 sensor circuit malfunction (bank 1) sensor 2

• P0137: O2 sensor circuit low voltage (bank 1) sensor 2

  An oxygen sensor’s voltage stays too low, which, on the common type of sensor, reads as a lean mixture (too much oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is lean.

  Common causes: faulty oxygen sensor, signal wire shorted to earth, or a damaged connector, exhaust leak in front of the sensor, vacuum leak or low fuel pressure making the mixture lean.

• P0138: O2 sensor circuit high voltage (bank 1) sensor 2

  An oxygen sensor’s voltage stays too high, which, on the common type of sensor, reads as a rich mixture (too little oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is rich.

  Common causes: faulty or contaminated oxygen sensor, signal wire shorted to a voltage, or a damaged connector, leaking injector or fuel pressure too high, making the mixture rich.

• P0140: O2 sensor circuit no activity detected (bank 1) sensor 2

• P0142: O2 Sensor Circuit Bank 1 Sensor 3

• P0143: O2 Sensor Circuit Low Voltage Bank 1 Sensor 3

  An oxygen sensor’s voltage stays too low, which, on the common type of sensor, reads as a lean mixture (too much oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is lean.

  Common causes: faulty oxygen sensor, signal wire shorted to earth, or a damaged connector, exhaust leak in front of the sensor, vacuum leak or low fuel pressure making the mixture lean.

• P0144: O2 Sensor Circuit High Voltage Bank 1 Sensor 3

  An oxygen sensor’s voltage stays too high, which, on the common type of sensor, reads as a rich mixture (too little oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is rich.

  Common causes: faulty or contaminated oxygen sensor, signal wire shorted to a voltage, or a damaged connector, leaking injector or fuel pressure too high, making the mixture rich.

• P0146: O2 Sensor Circuit No Activity Detected Bank 1 Sensor 3

• P0150: O2 sensor circuit malfunction (bank 2) sensor 1

• P0151: O2 Sensor Circuit Low Voltage Bank 2 Sensor 1

  An oxygen sensor’s voltage stays too low, which, on the common type of sensor, reads as a lean mixture (too much oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is lean.

  Common causes: faulty oxygen sensor, signal wire shorted to earth, or a damaged connector, exhaust leak in front of the sensor, vacuum leak or low fuel pressure making the mixture lean.

• P0152: O2 Sensor Circuit High Voltage Bank 2 Sensor 1

  An oxygen sensor’s voltage stays too high, which, on the common type of sensor, reads as a rich mixture (too little oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is rich.

  Common causes: faulty or contaminated oxygen sensor, signal wire shorted to a voltage, or a damaged connector, leaking injector or fuel pressure too high, making the mixture rich.

• P0154: O2 Sensor Circuit No Activity Detected Bank 2 Sensor 1

• P0156: O2 Sensor Circuit Bank 2 Sensor 2

• P0157: O2 Sensor Circuit Low Voltage Bank 2 Sensor 2

  An oxygen sensor’s voltage stays too low, which, on the common type of sensor, reads as a lean mixture (too much oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is lean.

  Common causes: faulty oxygen sensor, signal wire shorted to earth, or a damaged connector, exhaust leak in front of the sensor, vacuum leak or low fuel pressure making the mixture lean.

• P0158: O2 Sensor Circuit High Voltage Bank 2 Sensor 2

  An oxygen sensor’s voltage stays too high, which, on the common type of sensor, reads as a rich mixture (too little oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is rich.

  Common causes: faulty or contaminated oxygen sensor, signal wire shorted to a voltage, or a damaged connector, leaking injector or fuel pressure too high, making the mixture rich.

• P0160: O2 Sensor Circuit No Activity Detected Bank 2 Sensor 2

• P0162: O2 Sensor Circuit Bank 2 Sensor 3

• P0163: O2 Sensor Circuit Low Voltage Bank 2 Sensor 3

  An oxygen sensor’s voltage stays too low, which, on the common type of sensor, reads as a lean mixture (too much oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is lean.

  Common causes: faulty oxygen sensor, signal wire shorted to earth, or a damaged connector, exhaust leak in front of the sensor, vacuum leak or low fuel pressure making the mixture lean.

• P0164: O2 Sensor Circuit High Voltage Bank 2 Sensor 3

  An oxygen sensor’s voltage stays too high, which, on the common type of sensor, reads as a rich mixture (too little oxygen in the exhaust). Either the sensor or its wiring is at fault, or the mixture really is rich.

  Common causes: faulty or contaminated oxygen sensor, signal wire shorted to a voltage, or a damaged connector, leaking injector or fuel pressure too high, making the mixture rich.

• P0166: O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3

Can I keep driving?

The car usually drives normally. Without a working front sensor, though, the engine computer runs on a preset mixture: fuel use and emissions rise, and a mixture that stays too rich can overheat the catalytic converter.

If the engine hesitates, runs rough or stalls, or misfire codes appear, have it checked before driving far. If the check engine light flashes, stop when it’s safe to do so.

Symptoms

• Often just the check engine light, especially for the sensors behind the catalytic converter.
• Higher fuel use.
• On some cars, hesitation, a rough idle or black smoke when a front sensor is at fault.
• The Oxygen sensor or Catalyst self-test not complete under emissions readiness.

Common causes

• Faulty oxygen sensor. Sensors age, and oil or coolant burning in the engine, or unsuitable sealant, can contaminate them.
• Wiring or connector fault. The wiring runs close to the hot exhaust, so check it for melted insulation, chafing and corroded pins.
• Faulty sensor heater, which keeps the sensor too cold to work. A cold sensor gives no useful signal. A heater code, such as P0135, stored at the same time points this way.
• Exhaust leak near the sensor. Outside air drawn in through the leak upsets the reading.

Typical fixes

1. Read all fault codes, and fix fuel mixture, misfire and heater faults first: they can set these codes too.
2. Check the sensor’s connector and its wiring along the exhaust.
3. Check the exhaust in front of the sensor for leaks.
4. Watch the sensor in live data on a warm engine, if your car reports it. A front sensor should keep changing; a rear sensor is usually steadier.
5. Replace the sensor with the type specified for your car, clear the code, and check that the Oxygen sensor self-test completes.

Questions

Related codes

• P0133O2 sensor circuit slow response (bank 1) sensor 1
• P0135O2 sensor heater circuit malfunction (bank 1) sensor 1
• P0171System too lean (bank 1)
• P0420Catalyst system efficiency below threshold (bank 1)

• All explained fault codes
• More about this: Oxygen sensors explained
• More about this: Reading live data: what’s normal