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P0140 OBD-II O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2 Trouble Code




The P0140 code is an OBD-II trouble code for “02 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)” and indicates a fault in the operation of the oxygen sensor located in the exhaust system of a vehicle.

In this article, I will be talking about the P0140 trouble code, its symptoms, causes, and how to fix it.

What Does The P0140 Code Mean?

P0140 OBD-II O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2 Trouble Code

The P0140 trouble code appears when there is a significant issue with your car’s post-catalytic oxygen sensor. The P0140 trouble code means that the oxygen sensors built into the car have stopped working, and Sensor 2 of Bank 1 is not working.

These oxygen sensors are placed behind the catalytic converter, which regulates exhaust emissions.

The oxygen sensors monitor and evaluate the intensity of the converter’s exhaust. The Power Control Module (PCM) of the car figures out what the data and values that the oxygen sensors record mean.

The PCM regulates the converted emissions and modifies the overall performance of the engine. If the oxygen sensors are faulty, the Power Control Module will record the P0140 trouble code.

The data logged by oxygen sensors are used by the car’s exhaust emissions system. Oxygen sensors operate at optimal voltage ranges based on oxygen content.

Catalytic converters send low voltage if they detect a significant amount of oxygen, and vice versa.

If your car’s catalytic converter works at its best, it will make controlled exhaust emissions. The P0140 trouble code appears when the O2 sensors do not detect oxygen values in the specified ranges.

(Related: O2 Sensors In Cars: Everything You Need To Know)

Which Models Are Affected By The P0140 Code

MakeAffected By P0140 Code

What Are The Possible Causes of the P0140 Code?

The P0140 trouble code is caused when the vehicle’s computer detects no activity from the O2 sensor’s circuit on bank 1 sensor 2 which is the O2 sensor located within the exhaust system.

The oxygen sensors built into Bank 1 serve as pollution indicators, sending constant signals to the main ECM.

Any problem with the O2 sensors reduces the efficiency of the catalytic converter and results in error code P0140. To determine the root cause, thoroughly examine the bank 1 and O2 sensors.

The following are some of the possible causes of the P0140 trouble code.

  • Faulty or damaged sensors
  • The problem in the primary circuit and wiring
  • In the PCM there is a hardware or software problem
  • Damaged wires and connectors
  • The liquid in the harness connector
  • Melted harness due to direct warmth from the exhaust
  • Carbon and soot accumulation on sensors

(Related: P0138 OBD-II O2 Sensor Circuit High Voltage Bank 1 Sensor 2 Trouble Code)

What Are The Common Symptoms of The P0140 Code?

When the PCM detects the P0140 trouble code, the check engine light illuminates to alert the driver. Every vehicle’s catalytic converter loses efficiency in controlling emissions over time.

The error code P0140, on the other hand, does not affect the vehicle’s overall drivability. Nonetheless, it would be best if you repaired it to avoid further complications.

Here are the most common symptoms of the P0140 trouble code:

  • The check engine light illuminating the dashboard
  • Higher gas emission levels from the tailpipe or the silencer
  • Failed and incomplete test for the vehicle emission
  • Air-to-fuel ratio compromise
  • Pump noise in the air injection system
  • Engine fluctuations while accelerating and decelerating

(Related: P0131 OBD-II O2 Sensor Circuit Low Voltage Bank 1 Sensor 1 Trouble Code)

Is It Safe To Drive With a P0140 Code

Yes, driving with the P0140 trouble code is safe, but only for a short time. If this code is caused by a lean air-to-fuel ratio, driving with it for an extended period may result in increased engine damage.

While it is not a code you should ignore, it is not as serious as most other check engine light codes. There’s a good chance that everything is still working properly.

The real reason you need to fix a P0140 code is that you don’t know for sure that everything is working properly. If another issue arises with your vehicle, it has no way of informing you.

Furthermore, nothing is checking on the oxygen sensors. So you won’t know if the catalytic converter or the oxygen sensor stops working. This means you could have higher-than-normal emissions and hotter exhaust without even realizing it.

This can eventually cause premature wear of various parts, but when compared to other check engine lights, a code P0140 is about as mild as it gets.

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

How To Diagnose The P0140 Code

To diagnose the P0140 trouble code, you should follow the steps below.

  1. Scan for trouble codes and document freeze frame data by using the OBD-II scanner.
  2. Inspect the O2 sensor and its wiring for any signs of damage or wear. Look for broken wires, corroded connectors, or other issues that could affect the signal sent by the sensor.
  3. Use a multimeter to check the voltage signal of the O2 sensor while the engine is running. Compare the reading to the manufacturer’s specifications to determine if the sensor is functioning properly.
  4. Inspect the exhaust system for any signs of damage or leaks that could affect the performance of the O2 sensor.
  5. Check the fuel system for any issues that could cause a lean or rich fuel mixture, which could affect the readings of the O2 sensor. This may include checking the fuel pressure, fuel injectors, or fuel filter.
  6. Test the engine control module (ECM) and other related components for proper operation.
  7. Clear any stored trouble codes and test drive the vehicle to see if the P0140 code returns.

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

Most Common Mistakes When Diagnosing The P0140 Code

When the P0140 trouble code occurs, the O2 sensors and their circuits are likely to be compromised. Before replacing airflow sensors and injection pumps, you should check for the error code P0140.

Furthermore, before replacing the entire air injection pump and its circuit, the burnt wires and connectors must be repaired or replaced. You should also inspect the O2 sensors for contamination and moisture.

How Much Does It Cost To Repair P0140 Code

O2 sensor cost: $59.21

Mass airflow sensor cost: $97.99

Labor cost: $150

MakeP0140 CodeRepair Cost
ToyotaYes$209.21 – $247.99
NissanYes$209.21 – $247.99
ChevroletYes$209.21 – $247.99
BMWYes$209.21 – $247.99
AudiYes$209.21 – $247.99
BuickYes$209.21 – $247.99
MercedesYes$209.21 – $247.99
GMCYes$209.21 – $247.99
SuzukiYes$209.21 – $247.99
TataYes$209.21 – $247.99
LexusYes$209.21 – $247.99
MazdaYes$209.21 – $247.99
MitsubishiYes$209.21 – $247.99
KiaYes$209.21 – $247.99
JeepYes$209.21 – $247.99
FiatYes$209.21 – $247.99
HondaYes$209.21 – $247.99
HyundaiYes$209.21 – $247.99
OpelYes$209.21 – $247.99
FordYes$209.21 – $247.99
FiatYes$209.21 – $247.99
PeugeotYes$209.21 – $247.99

What Repairs Can Fix The P0140 Code?

Repairs that can fix the P0140 trouble code include the following:

  • Check to see if the O2 sensor changes when the fuel mixture is enriched.
  • Test the mass airflow sensor for proper readings according to specifications.
  • Replace the 02 sensors if it is contaminated or fail the tests.
  • Replace the mass airflow sensor if it is polluted or fails the test.
  • Check to see if the readings change after cleaning the mass airflow sensor.

(Related: How To Clean O2 Sensor Without Removing It)

How To Fix The P0140 Code

To fix the P0140 trouble code, you need to:

  • Replace faulty oxygen sensor
  • Repair or replace the damaged or corroded wiring or connectors
  • Fix any leaks in the exhaust system
  • Check for clogged fuel filters or faulty fuel injectors and repair them.
  • Clean the mass air flow sensor to determine whether this fixes the problem.
  • Replace defective mass airflow sensor

In Conclusion

Every engine and its components require routine maintenance and cleaning. To avoid DTC error codes, it is critical to maintain your vehicle’s overall health and condition.

Before replacing the entire circuit and O2 sensors, a qualified mechanic should be consulted.

To avoid engine malfunction and excessive fuel consumption, the trouble code P0140 must be resolved as soon as possible.



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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