Fault code P0143 – oxygen O2 sensor circuit low voltage (Bank 1, Sensor 3)

Fault code P0143 is called “Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 3)” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0143

This diagnostic trouble code (DTC) is a generic code. Error P0143 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P0143 – oxygen O2 sensor circuit low voltage (Bank 1, Sensor 3)

Diagnostic code P0143 refers to the third oxygen sensor (O₂), located on Bank 1, after the catalytic converter. This sensor measures the amount of oxygen entering the exhaust gases.

It plays an important role in the control circuit, which constantly checks the correctness of the fuel-air mixture. It sends a signal that is used to support fuel feedback.

The meaning of this code is that the O₂ (oxygen sensor) voltage has been low for more than 2 minutes. This is perceived by the engine control module (ECM) as a low voltage condition and consequently error code P0143 OBD2 is set.

Symptoms of vehicle malfunctions

The main signal that an error P0143 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine indicator light on the control panel is on.
  2. Increased fuel consumption.
  3. Excessive smoke from the exhaust pipe.

Fault P0143 may indicate a failure of the oxygen sensor, so the ECM will not be able to adjust the air-fuel mixture ratio normally. This may result in increased fuel consumption, as well as problems with the engine and exhaust system performance of the vehicle.

Factors that can cause this error code

The error code P0143 can mean that one or more of the following problems have occurred:

  • The oxygen sensor O₂ may be defective.
  • There may be a voltage short circuit in the oxygen sensor signal circuit O₂.
  • High resistance or open circuit in the oxygen sensor signal circuit O₂.

How to fix or reset OBD-2 code P0143

Some suggested steps for troubleshooting and fix the error code P0143:

  1. Replace the faulty sensor.
  2. Eliminate short circuit, open circuit or high resistance in the signal circuit O₂.

Diagnose and repair of problems

It is necessary to read out all saved data and error codes with an OBD-II scanner. Clear the error codes from the computer memory and test-drive the vehicle. To find out if code P0143 appears again.

To check the oxygen sensor voltage in real time using a scan tool. To find out if the sensor is working properly. Inspect the oxygen sensor electrical wires and connector for corrosion and damage.

Inspect the oxygen sensor for fluid contamination and damage. Test the exhaust system for exhaust gas leaks, and repair any leaks present, if necessary.

On which vehicles does this problem occur most frequently

Fault code P0143 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi (A6)
  • Cadillac (DeVille, Eldorado)
  • Chevrolet (Blazer, Silverado)
  • Citroen
  • GMC (Sonoma)
  • Honda
  • Iveco
  • Mazda
  • Mitsubishi
  • Toyota (Camry)
  • Volkswagen (Golf)
  • GAZelle (Business)
  • VAZ (2112)

Fault code P0143 can sometimes be found with other errors. The most common are the following: P0101, P0131, P0151, P0155.

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