Description of fault code P0142,
OBD2 Error Codes

P0142 Oxygen sensor 3 bank 1 circuit malfunction

26.05.2022 /

P0142 – OBD-II Trouble Code Technical Description

Trouble code P0142 indicates a malfunction in the oxygen sensor 3 (bank 1) circuit.

What does the fault code mean P0142?

Trouble code P0142 indicates problems with the heater oxygen (O₂) sensor, which is located on the first bank of the engine (usually closest to the cylinder head) and is designed to measure the oxygen content of the exhaust gases. This sensor has a built-in heater that helps it reach operating temperature faster and improves its accuracy. Code P0142 indicates a failure in the oxygen sensor heater.

Oxygen sensor 3, bank 1.

Possible reasons

Some possible causes of the P0142 trouble code:

  • Damaged or failed oxygen sensor heating element.
  • The wiring or connectors connecting the oxygen sensor to the electronic control module (ECM) are broken or corroded.
  • There is a malfunction in the electronic control module (ECM).
  • Problems with the fuse or relay that powers the oxygen sensor heater.
  • Incorrect installation or damage to the oxygen sensor.
  • Problems with the vehicle's electrical system, such as power supply voltage, grounding, or other electrical noise.

What are the symptoms of a fault code? P0142?

Possible symptoms for DTC P0142:

  • Increased fuel consumption: If the oxygen sensor is not functioning properly, it can result in an incorrect mixture of fuel and air, which can cause increased fuel consumption.
  • Unstable motor: An incorrect fuel/air mixture can also cause the engine to run rough, idle poorly, or even cause the idle speed to jump.
  • Increased emissions: A malfunctioning oxygen sensor can lead to increased emissions of harmful substances in the exhaust gases.
  • Engine performance deterioration: If the ECM goes into limp mode due to unavailability of information from the oxygen sensor, this may result in reduced engine power and other malfunctions.
  • An error appears on the instrument panel: In some cases, the Check Engine light or other emissions related warning lights may come on.

How to diagnose a fault code P0142?

To diagnose the P0142 oxygen sensor trouble code, follow these steps:

  1. Check the connection and wires: Check the condition of the connections and wires leading to the oxygen sensor. Make sure they are not damaged and are well secured.
  2. Check resistance: Use a multimeter to check the resistance at the oxygen sensor wires and connectors. Make sure that the resistance values ​​are within the normal range as specified in the technical documentation for your specific vehicle make and model.
  3. Check the supply voltage: Using a multimeter, check the supply voltage at the oxygen sensor connector. Make sure the voltage meets the manufacturer's specifications.
  4. Check signal wires: Check the oxygen sensor signal wires for corrosion, breaks, or other damage. Replace damaged wires if necessary.
  5. Check the condition of the oxygen sensor: If all the previous steps do not resolve the problem, the oxygen sensor may be faulty and need to be replaced. This usually involves removing the sensor and checking its resistance or voltage using a multimeter.
  6. Check ECM: If all other components check and function properly, the problem may be with the Engine Control Module (ECM). In this case, additional diagnostics will be required, carried out by a qualified specialist using specialized equipment.

Diagnostic errors

When diagnosing DTC P0142, the following errors may occur:

  • Incorrect interpretation of data: The error may occur due to incorrect interpretation of the data received from the oxygen sensor. Misunderstanding voltage or resistance values ​​can lead to incorrect conclusions about the sensor's condition.
  • Incorrect cause identification: Another common mistake is incorrectly identifying the cause of the problem. Some mechanics may immediately assume that the problem is with the oxygen sensor itself without checking for other possible causes, such as damaged wires or problems with the ECM.
  • Lack of checking additional components: Sometimes mechanics may skip checking other exhaust system components, such as the catalytic converter or air filter, which can also trigger the P0142 trouble code.
  • Using unsuitable equipment: Some errors may occur due to the use of inappropriate equipment or insufficient qualifications of the technician when performing diagnostics. Using the wrong type of multimeter or not fully understanding how the system works can lead to incorrect conclusions.

To prevent these errors, it is important to have a good understanding of the engine management system, correctly interpret the data and perform comprehensive diagnostics using the appropriate equipment and techniques.

How serious is the fault code? P0142?

Trouble code P0142 indicates problems with the oxygen sensor. Although this code is not one of the most serious, it still requires careful attention and repair. A malfunctioning oxygen sensor can result in poor engine performance, increased emissions, and even loss of power and increased fuel consumption. It is important to quickly detect and repair this problem to avoid more serious problems in the future.

What repair will help eliminate the code? P0142?

To resolve DTC P0142, follow these steps:

  1. Checking wiring and connectors: Check the wiring and connectors connecting the oxygen sensor to the engine control module (ECM). Make sure the wires are not broken or burned and are securely connected.
  2. Resistance test: Check the resistance on the oxygen sensor circuit. It must be within the manufacturer's specifications. If the resistance is not up to standard, the oxygen sensor may be faulty and needs to be replaced.
  3. Replacing the oxygen sensor: If the oxygen sensor is faulty, it should be replaced with a new original or high-quality analogue.
  4. Checking the Engine Control Module (ECM): In rare cases, the problem may be with the engine control module itself. If other causes have been ruled out, the ECM may require diagnosis or replacement.
  5. Clearing errors and re-diagnosis: After repairs are completed, clear the DTC from the ECM using a diagnostic scanner. Then re-test to make sure the problem is resolved.

If you do not have experience in carrying out this work, it is recommended that you contact a qualified auto mechanic or auto repair shop for diagnosis and repair.

How to Fix P0142 Engine Code in 4 Minutes [3 DIY Methods / Only $9.35]

P0142 – Brand-specific information

Information about the P0142 fault code may vary depending on the vehicle manufacturer, a list of several car brands with explanations:

These are just some of the possible interpretations of the P0142 code for various makes of vehicles. For accurate information, it is recommended to consult the repair manual for your specific vehicle make and model.

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