P CODES (POWERTRAIN) P0100 - P0199 P0142

Definition of Trouble Code P0142: Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 3)

Trouble code P0142 is related to the oxygen sensor circuit malfunction in the exhaust system. The oxygen sensor (O2 sensor) is responsible for monitoring the level of oxygen in the exhaust gases, allowing the engine control module (ECM) to adjust the air-fuel mixture for optimal engine performance and emissions. Specifically, this code refers to a malfunction in the bank 1 sensor 3 oxygen sensor circuit.

How to Diagnose Trouble Code P0142

Diagnosing trouble code P0142 involves checking the oxygen sensor, its wiring, and the ECM. Follow these steps to diagnose the issue:

Step 1: Locate the oxygen sensor. Bank 1 sensor 3 is usually located after the catalytic converter. Refer to your vehicle's repair manual for the exact location.

Step 2: Perform a visual inspection. Check for damaged or loose wiring, corrosion, or signs of wear on the oxygen sensor itself. Repair or replace any damaged components as needed.

Step 3: Check the sensor's voltage. Using a digital multimeter, probe the sensor's signal wire (refer to the repair manual for wire colors) while the engine is running. The voltage should fluctuate between 0.1 and 0.9 volts. If the voltage is not within this range, the sensor may be faulty and require replacement.

Step 4: Check the heater circuit. The oxygen sensor has a built-in heater to help it reach its optimal operating temperature quickly. Check the heater circuit's resistance with a multimeter. If the resistance is not within the manufacturer's specifications, the sensor should be replaced.

Step 5: Inspect the ECM. If all previous steps check out, the problem may lie with the ECM. Perform an ECM diagnostic using a scan tool and follow the manufacturer's recommendations for repair or replacement if necessary.

How to Repair Trouble Code P0142

Depending on the diagnosis, the following repairs may be necessary to resolve trouble code P0142:

1. Replace the oxygen sensor: If the sensor is faulty or has reached the end of its service life, it will need to be replaced. Make sure to use an oxygen sensor that is compatible with your vehicle.

2. Repair or replace damaged wiring: If you find damaged or loose wiring during the visual inspection, repair or replace it as needed to ensure proper oxygen sensor function.

3. Replace the ECM: In rare cases, the ECM may be the cause of the P0142 code. If the ECM diagnostic indicates an issue, follow the manufacturer's recommendations for repair or replacement.

Conclusion

Trouble code P0142 is a common issue related to the oxygen sensor circuit. By following the steps outlined in this guide, you can diagnose and repair the problem, ensuring optimal engine performance and emissions. Always consult your vehicle's repair manual for specific information about your make and model and follow all safety precautions when working on your vehicle.