Error P0131 – how to fix?

Code definition P0131

Code P0131 is bank 1 oxygen sensor low voltage or incorrect air-fuel ratio.

What does the code P0131 mean

• Code P0131 indicates that there is a fault with the oxygen sensor located in bank 1 of the vehicle sensor 1. It is also called air / fuel sensor or heated O2 sensor. This means the ECU has detected the wrong oxygen sensor voltage or the wrong air-fuel ratio.
• Bench 1 refers to the left side of the engine when seated in the driver’s seat. Sensor 1 refers to a sensor located upstream of the catalytic converter in the exhaust system.

What causes the code P0131?

P0131 can be caused by various problems:

• Oxygen sensor failure
• Wiring damaged or disconnected
• Open or short circuit
• Incorrect coolant temperature sensor reading
• Oxygen sensor heating circuit failure
• Most often, the sensor simply failed due to age and wear.

What are the symptoms of the P0131 code?

When a malfunction is detected in the oxygen sensor circuit, the Check Engine light illuminates and is visible on the instrument panel. When the Check Engine light comes on, the car’s ECU puts the car into safety mode, sets the air-fuel ratio to a steady state, and tilts the vehicle to prevent damage to the catalytic converter. Low fuel consumption can be observed in tilted conditions.

The vehicle may run sluggishly or stall while driving with an oxygen sensor problem. In extreme cases, the vehicle’s engine may stall while working with this code.

How can a mechanic diagnose the P0131 code?

The first thing any mechanic will do is connect an OBD2 scanner to the DLC connector, usually located under the driver’s side dash, to read and confirm the current codes. Each code will have a frozen frame data associated with it which tells us under what conditions such as engine speed, driving speed, running time, engine temperature that the code has been set, so we can recreate it on our test drive.

Once P0131 is confirmed, a qualified mechanic will clear the code and take the vehicle for a test drive observing the datastreme vehicle which will show the voltage and resistance of the oxygen sensor. If the code reappears, excessive resistance displays, or an out-of-range voltage is present, the technician has confirmed that there is a fault in the oxygen sensor circuit.

The first thing a qualified technician will do is perform a visual inspection to ensure the integrity of the oxygen sensor wiring.

If the wiring is OK, the mechanic will check the voltage and resistance of the sensor. The voltage should be below 1 V and the resistance below the manufacturer’s specification for each vehicle.

The most common errors when diagnosing the P0131 code

• The most common error is the failure to acknowledge the fault in the oxygen sensor circuit by deleting the code and performing a test drive.
• Another common error is that engine failure may be due to an oxygen sensor failure or, alternatively, engine failure may result in incorrect vehicle oxygen sensor readings.
• In addition, a defective coolant temperature sensor can also lead to misdiagnosis.

How serious is the P0131 code?

The P0131 code may indicate a serious problem that could cause the vehicle to malfunction and shut down while driving. Be careful if you encounter this code and fix it quickly.

What repairs can fix the code P0131?

1. Confirm the presence of P0131 with a scan tool. Clear fault code and perform road test ensuring P0131 returns.
2. Visually inspect the bank 1 sensor wiring by replacing or repairing any wiring found to be defective.
3. Check the voltage and resistance of the bank sensor 1.
4. If necessary, replace the bank 1 oxygen sensor with a new one.

Additional notes regarding code P0131

• Oxygen sensors are designed to last the life of the vehicle, but it is not uncommon for oxygen sensor problems to arise as the vehicle ages after 100,000 miles.
• This code causes driving problems, poor fuel economy and potential engine damage, so it should be addressed as soon as possible.