my Honda Civic 11th Generation (2022-Present) has a check engine light and code P0420, what does it...

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Test Oxygen Sensors

• Use a multimeter to check the voltage output of the upstream oxygen sensor.
  • Expected Voltage: Fluctuates between 0.1 to 0.9 volts.
• If the upstream sensor is faulty, replace it using the following steps:
  1. Remove wiring harness and unbolt the sensor using a socket wrench.
  2. Install the new sensor and reconnect the harness.

3. Inspect and Test Catalytic Converter

1. Check for physical damage or blockage in the catalytic converter.
2. If necessary, remove the catalytic converter:
   • Use a socket set to unbolt the converter from the exhaust system.
   • Inspect internal components for signs of failure (e.g., melted substrate).
3. If the converter is defective, replace it:
   • Install the new catalytic converter and secure with bolts to manufacturer torque specifications.

4. Clear Error Codes

• Reconnect the battery and use the OBD-II scanner to clear the check engine light codes.
• Confirm the repairs by running the engine and checking for reoccurrence of the P0420 code.