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P0131 OBD-II O2 Sensor Circuit Low Voltage Bank 1 Sensor 1 Trouble Code




The P0131 trouble code stands for 02 Sensor Circuit Low Voltage Bank 1 Sensor 1 and it is triggered when the vehicle’s computer detects a low-voltage signal from the front oxygen sensor, which detects the amount of oxygen in the raw exhaust gas.

In this article, I will be talking about the P0131 trouble code, its symptoms, causes, and how to fix it.

What Does The P0131 Code Mean?

P0131 OBD-II O2 Sensor Circuit Low Voltage Bank 1 Sensor 1 Trouble Code

The P0131 trouble code means that the vehicle’s #1 O2 sensor isn’t giving correct information about the #1 engine bank. This component is also known as the air/fuel sensor. The ECM/PCM of a car uses data from this sensor to figure out the best ratio of air to fuel for the car to run efficiently.

So, the P0131 code means that there is something wrong with the #1 oxygen sensor (bank 1). Simply said, the ECU, ECM, or PCM of the concerned car has received sensor feedback that is illogical or significantly outside the typical operating range. So, operating logic causes the management software of an engine to reject such input.

To get around any problems this might cause, the engine starts to work in failsafe mode, which uses pre-programmed data to replace any iffy sensor feedback. These characteristics permit a motor to continue operating but in a suboptimal manner. Frequently, a decline in fuel economy will become apparent.

(See also: Can a Bad O2 Sensor Cause a Misfire? (Answered!))

Which Models Are Affected By The P0131 Code

MakeAffected By P0131 Code

What Are The Possible Causes of the P0131 Code?

The P0131 code is caused when the vehicle’s computer detects a low-voltage signal from the oxygen sensor.

The diagnostic trouble code P0131 can be caused by several different problems. These problems often affect one or more of a car’s O2 sensors or circuits that work with them.

Many of the most prevalent causes of the P0131 trouble code are listed below.

  • Defective 02 sensor
  • Open or shorted 02 sensor circuit
  • 02 sensor connector is damaged or loose
  • Leaks in the exhaust/intake system
  • Faulty engine coolant temperature sensor
  • Engine control module (ECM) issues

What Are The Common Symptoms of The P0131 Code?

There are several additional symptoms that often accompany the start of the P0131 trouble code. However, these symptoms may vary from case to case.

Below are several of the most common symptoms linked with diagnostic trouble code P0131.

  • Check engine light
  • Low fuel economy
  • Erratic or rough idle
  • Lack of power
  • Starting difficulties
  • In some cases, there are no adverse conditions

Is It Safe To Drive With a P0131 Code

Yes, it is safe to drive with the P0131 trouble code, but only for a short period of time. Driving with this code for an extended period of time may result in increased engine damage if it is caused by a lean air-to-fuel ratio.

The diagnostic trouble code P0131 is generally viewed as a serious condition. Due to the fact that code P0131 can ultimately result in stalling and other significant drivability problems. So, if this kind of problem isn’t fixed, it can leave a driver stuck, maybe in the middle of traffic.

In any case, the trouble code P0131 should be treated seriously and dealt with immediately. If you don’t think you can figure out what’s wrong and fix it yourself, you should make an appointment as soon as possible with a reputable service center.

(See also: P2195 OBD-II O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Trouble Code)

How To Diagnose The P0131 Code

If you want to easily diagnose the P0131 trouble code, you should follow the steps below.

  1. Plug in the OBD-II scan tool to pull the trouble code, preserve the freeze frame data, and clear the trouble code. Then, conduct a test drive to determine whether the check engine light is still blinking or whether the code is still set.
  2. Check the oxygen sensor’s wiring and harness connector for corrosion or damage.
  3. Check the HO2S voltage and resistance with a millimeter. The voltage of the sensor should be less than 1 volt, and the resistance should conform to the manufacturer’s specifications.
  4. Make a review of coolant temperature sensor issues, low fuel pressure, and vacuum or exhaust leaks.

A thorough diagnostic can aid in preventing unneeded replacements, reducing the cost of your repairs. For example, a misfiring engine can cause the O2 sensor to give wrong readings. This means that the O2 sensor is not defective and that another part needs to be fixed.

Most Common Mistakes When Diagnosing The P0131 Code

Here are the most common mistakes when diagnosing the P0131 code:

  • Most people make the mistake of not clearing the fault code and taking the car for a test drive to see if the problem is in the oxygen sensor circuit.
  • Another common mistake is to think that a bad oxygen sensor can cause an engine to misfire or that a bad engine can cause the oxygen sensors to read wrong.
  • Misdiagnoses can also happen if the coolant temperature sensor is faulty.

How Much Does It Cost To Repair P0131 Code

It costs between $34 and $150 to repair a P0131 code. The O2 sensor costs between $34 and $54 while labor is usually between $80 and $100.

MakeP0131 CodeRepair Cost
ToyotaYes$34 – $150
NissanYes$34 – $150
ChevroletYes$34 – $150
BMWYes$34 – $150
AudiYes$34 – $150
BuickYes$34 – $150
MercedesYes$34 – $150
GMCYes$34 – $150
SuzukiYes$34 – $150
TataYes$34 – $150
LexusYes$34 – $150
MazdaYes$34 – $150
MitsubishiYes$34 – $150
KiaYes$34 – $150
JeepYes$34 – $150
FiatYes$34 – $150
HondaYes$34 – $150
HyundaiYes$34 – $150
OpelYes$34 – $150
FordYes$34 – $150
FiatYes$34 – $150
PeugeotYes$34 – $150

What Repairs Can Fix The P0131 Code?

Repairs that can fix the P0131 code include the following:

  • Use a scan tool to make sure that P0131 is present. Clear the trouble code and do a road test to see if P0131 shows up again.
  • Do a visual examination of the bank 1 sensor 1 wiring, replacing or fixing any faulty wiring discovered.
  • Check the voltage and resistance of bank 1 sensor 1
  • Replace the oxygen sensor bank 1, sensor 1, if necessary, with a new sensor.

How To Fix The P0131 Code

To fix the P0131 code, you need to:

  • Visually inspect the oxygen sensor and wiring for any signs of damage
  • Use a scan tool to monitor the oxygen sensor data
  • Test the oxygen sensor’s voltage, current, and ground signals
  • Check the wiring harness and connectors for any loose or corroded connections
  • Replace any faulty parts, such as the oxygen sensor or wiring
  • Clear the trouble code and test drive the vehicle to ensure the issue is resolved

In Conclusion

A defective O2 sensor is nothing to mess around with. Whether you can resolve this issue on your own or need to take it to a repair shop, do so immediately.

You don’t want your vehicle to stall in the midst of a busy junction and cause an accident, or even worse, leave you stuck in a parking lot or on the side of the road.

Immediate diagnosis and repair are essential for maintaining the operability of your vehicle.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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