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

P0143 Code O2 Sensor Circuit Low Voltage Bank 1 Sensor 3

The oxygen sensor in a car monitors the amount of oxygen in the exhaust. This information is used by the car’s computer to adjust the fuel mixture and optimize performance. If the sensor is not working properly, it can cause the engine to run too rich or too lean, resulting in poor performance.

The P0143 code is related to the O2 sensor circuit low voltage on bank 1 sensor 3. This indicates that the voltage from the sensor to the computer is lower than what is expected. The purpose of this article is to provide information on the P0143 code, which is an indication that the O2 sensor circuit voltage is low on bank 1 sensor 3. The article will provide information on the symptoms of this code, as well as possible causes and solutions.

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

Rear Oxygen Sensors On Dual Exhaust System
Rear Oxygen Sensors On Dual Exhaust System

O2 Sensor Circuit Low Voltage Bank 1 Sensor 3 is referred to as P0143. It is recorded when the bank 1 sensor 3 post-catalytic converter oxygen sensor or its circuit is suspected of having an issue by the powertrain control module (PCM). Depending on the car manufacturer, the definition of code P0143 may vary. For the precise definition of the code, consult the relevant repair manual or database.

The oxygen sensor, which is placed at the back of the catalytic converter sensor 2, monitors the efficiency of the catalytic converter in reducing emissions. This information is used by the Powertrain Control Module to determine if the converter is in good operating order.

If the car computer (PCM) detects the efficiency of the catalytic converter below a certain threshold, which could result in low voltage output from the rear O2 sensor, the PCM will set the P0341 error code. This code is triggered when the engine’s rear oxygen sensor fails to produce a voltage reading within a specific range.

This error code refers to a sensor that is located behind the catalytic converter on bank 1 (side of cylinder 1) of the exhaust system and which inputs a low voltage to the car computer, perhaps resulting in excessive exhaust emission. Since the car computer does not use the code for fuel regulation, the engine will often not operate any differently as a result of it. If the Check Engine Light does not turn off, the vehicle will fail emission testing. There could be a leak in the exhaust, allowing exhaust fumes to enter the passenger area.

Related Post: How To Bypass Oxygen Sensor: 3 Guaranteed Methods

What Causes The P0143 Code

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

Because P0143 is a generic code, it can have several causes.

  • Air leaks in the exhaust system,
  • A faulty oxygen sensor
  • Wiring issues,
  • A defective PCM
  • A damaged connector
  • The O2 sensor’s signal, ground, or voltage circuit is shorted or open

What Are The Symptoms Of The P0143 Code

The following symptoms may result from a vehicle that has a logged p0143 engine code.

  • The check engine light is illuminated.
  • poor fuel economy
  • Engine running rich
  • Rough idle

How To Fix P0143 Code:

Although the P0143 engine code may have comparable causes and symptoms to other DTCs, it does not have a universal solution. Because vehicles are manufactured differently depending on the manufacturer, the diagnostic and repair processes for the code may differ. Following are the steps to fix the P0143 code.

  • First of all check for corroded, or cut wiring and connector. If you find corroded, cut or shorted wiring and connectors, it is important to address the issue as soon as possible. First, try cleaning the connectors with a wire brush or sandpaper. If that doesn’t work, you may need to replace the connector. If the wiring is damaged, you will need to replace the entire wire.
  • Secondly, check for catalyst leaks. When the exhaust leaks before the catalyst, it allows too much air to enter the system. This can cause the catalyst to the O2 sensor to read low voltage and not work properly. It is important to repair any leaks before replacing the catalyst to avoid this from happening.
  • Thirdly, if the above solutions don’t work then try to replace the oxygen sensor. The replacement oxygen sensor must be the same type as the original sensor.
  • Finally, replace the car computer (PCM). To replace the defective PCM, you will need to locate the PCM. The PCM is usually a rectangular box with a bunch of connectors coming out of it. There should be a sticker on it that has the part number on it. Once you have the part number, you can go to an automotive parts store and order a replacement. The replacement process is relatively simple – just remove the old PCM and replace it with the new one.

Common Errors While Diagnosis:

Following are some common errors while diagnosing the DTC P0143, which must be avoided.

  1. By proper testing and road test under the same circumstances as the initial failure, clear the codes and confirm sensor failure (found in the freeze frame data).
  2. In order to prevent the O2 sensor from functioning improperly, look for any exhaust leaks or damage to the exhaust manifold or header pipes before the sensor.

Cost For Fixing The P0143 Code:

Vehicles of various manufacturers and models may display code P0143. Other Diagnostic Trouble Codes may also have comparable causes and symptoms. When it comes to fixing the P0134 code, one or more of the following repairs may be required to resolve the underlying problem.

The estimated cost of repair for each conceivable repair includes the cost of the relevant parts as well as the cost of labor required to complete the repair. The cost of an oxygen sensor is between $200 and $300, and the cost of repairing exhaust leaks is between $100 and $200.


In conclusion, the P0143 code indicates that there is a problem with the O2 sensor circuit on Bank 1 Sensor 3. This can be caused by a number of things, such as a faulty oxygen sensor, a short in the wiring, a problem with the engine control module, etc. This can be a tricky problem to diagnose and fix, so if you suspect that your car is having this issue, it’s important to take it to a mechanic so they can diagnose and fix the problem.

Related Post: What Are Bank 1 And Bank 2: (O2 Sensor 1 & 2) Locate Easily

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