P0143 O₂ Sensor Circuit Low Voltage (Bank 1, Sensor 3)

P0143 – OBD-II Trouble Code Technical Description

DTC P0143 indicates low voltage in the oxygen sensor 3 (bank 1) circuit.

What does the fault code mean P0143?

Trouble code P0143 indicates a problem with oxygen sensor 3 (bank 1). This code is usually associated with low voltage at the oxygen sensor output.

Possible reasons

Some possible causes of the P0143 trouble code:

• Defective oxygen sensor (O2) in bank 1, sensor 3.
• Poor electrical connection or break in the wiring connecting the oxygen sensor to the engine control module.
• Engine control module (ECM) malfunction.
• Electrical problems such as a short circuit or broken wire.
• Fuel quality problems such as contamination or insufficient fuel pressure.
• Problems with the fuel injection system, such as a defective injector or fuel pressure regulator.

These causes should be considered when diagnosing DTC P0143.

What are the symptoms of a fault code? P0143?

Some possible symptoms when trouble code P0143 is present:

• Increased fuel consumption: A faulty oxygen sensor can result in an incorrect fuel/air mixture, which can increase fuel consumption.
• Unstable engine operation: If the fuel and air mixture is incorrect, the engine may run rough or rough.
• Slow acceleration response: A malfunctioning oxygen sensor can cause the engine to slow down when pressing the gas pedal.
• Increased emissions of harmful substances: Improper operation of the oxygen sensor can result in increased emissions of nitrogen oxides (NOx) and other harmful substances.
• Reduced performance: If the engine runs too lean or too rich due to a faulty oxygen sensor, it can result in poor vehicle performance.

These symptoms may occur to varying degrees depending on the specific problem and its impact on engine performance.

How to diagnose a fault code P0143?

To diagnose DTC P0143, follow these steps:

1. Checking connections: The first step is to check all electrical connections associated with the oxygen sensor. Make sure all connectors are securely connected and have no visible damage or corrosion.
2. Wiring check: Inspect the wiring for damage, breaks or corrosion. Check the wiring from the oxygen sensor to the corresponding connector on the engine control unit.
3. Resistance test: Use a multimeter to measure the resistance on the oxygen sensor wires. The resistance must meet the manufacturer's specifications.
4. Voltage check: Using a multimeter, measure the voltage on the oxygen sensor wires with the engine running. The voltage must fluctuate within a certain range specified by the manufacturer.
5. Replacing the oxygen sensor: If all of the above checks do not reveal the problem, the oxygen sensor may need to be replaced. Make sure the new sensor meets your vehicle's specifications.
6. Checking the Engine Control Module (ECM): In rare cases, the problem may be related to the engine control unit. If other tests do not reveal the cause of the malfunction, then additional ECM diagnostics using specialized equipment may be required.

It is important to follow the repair instructions provided by your vehicle's manufacturer and use the correct tools and techniques to diagnose and repair safely. If you do not have experience in carrying out such work, it is recommended that you contact a qualified auto mechanic.

Diagnostic errors

When diagnosing DTC P0143, the following errors may occur:

• Incorrect wiring diagnosis: Incorrect interpretation of wiring conditions or incorrect measurement of resistance or voltage on the oxygen sensor wires may lead to incorrect conclusions about the cause of the malfunction.
• Incorrect replacement of the oxygen sensor: Before replacing the oxygen sensor, you need to make sure that the problem is in the sensor and not in the wiring or engine control unit. An incorrect replacement may result in additional repair costs without addressing the root of the problem.
• Skipping other reasons: Sometimes the cause of the P0143 code may be related not only to the oxygen sensor, but also to other systems or components of the vehicle, such as the fuel injection system, ignition system, or engine control unit.
• Incorrect interpretation of data: Incorrect understanding of the data obtained during diagnostics, or their incorrect interpretation, can lead to an incorrect conclusion about the causes of the malfunction and incorrect actions to eliminate it.
• Skipping basic diagnostic steps: Skipping basic diagnostic steps, such as checking connections, wiring, and measuring voltage or resistance, may result in missing important details that affect diagnostic accuracy.

It is important to follow the diagnostic guidelines provided by the vehicle manufacturer and use the correct tools and techniques for accurate and efficient diagnosis and repair. If you do not have experience in carrying out such work, it is recommended that you contact a qualified auto mechanic.

How serious is the fault code? P0143?

Trouble code P0143 indicates a problem with the oxygen sensor. Although this can indicate various problems, such as improper engine operation or insufficient emission control system performance, it is usually not critical or emergency. However, ignoring it can lead to reduced fuel economy, poor engine performance and increased emissions of harmful substances into the environment. Therefore, it is recommended to diagnose and fix this problem as soon as possible.

What repair will help eliminate the code? P0143?

Troubleshooting DTC P0143 typically involves the following steps:

1. Oxygen Sensor Replacement: If the oxygen sensor fails or is defective, it should be replaced with a new one that meets the vehicle manufacturer's specifications.
2. Checking Wiring and Connections: Perform a thorough check of the wiring and connections associated with the oxygen sensor. Make sure the wiring is not damaged, the connectors are well connected and there is no corrosion.
3. Checking and replacing fuses: Check the fuses that supply the oxygen sensor power supply circuit. Replace them if necessary.
4. Diagnosis of Other Components: Check other engine management system components such as the throttle body, intake manifold, fuel injection system, and catalytic converter to rule out possible problems affecting oxygen sensor performance.
5. Software Update: In some cases, updating the software in the ECU may help resolve the problem.

If you are unsure of your automotive repair skills, it is recommended that you contact a professional mechanic or auto repair shop to diagnose and repair the problem.

How to Fix P0143 Engine Code in 4 Minutes [3 DIY Methods / Only $9.76]

P0143 – Brand-specific information

Trouble code P0143 is related to the oxygen sensor and can be found on various makes of vehicles. Below is a list of some of them with their transcripts:

1. Toyota: Insufficient oxygen sensor activity (Bank 1 Sensor 3)
2. Honda: Low Activity Oxygen Sensor (Bank 1 Sensor 3)
3. Ford: Low Activity Oxygen Sensor (Bank 1 Sensor 3)
4. Chevrolet: Low oxygen sensor activity (Bank 1 Sensor 3)
5. BMW: Oxygen sensor 3 (Bank 1 Sensor 3) – low activity level
6. Mercedes-Benz: Insufficient oxygen sensor activity (Bank 1 Sensor 3)
7. Volkswagen: Low level of oxygen sensor activity (Bank 1 Sensor 3)
8. Audi: Insufficient oxygen sensor activity (Bank 1 Sensor 3)
9. Subaru: Low oxygen sensor activity (Bank 1 Sensor 3)
10. Nissan: Low Activity Oxygen Sensor (Bank 1 Sensor 3)

Please refer to your specific vehicle's documentation for more specific information about the P0143 trouble code.