how to fix P0420 code in Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative terminal of the battery to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors (if necessary)

• If the upstream or downstream oxygen sensors are faulty:
  • Tools Required: O2 sensor socket, wrench set, torque wrench.
  • Sub-steps:
    1. Locate the oxygen sensors (usually near the exhaust manifold for upstream and after the catalytic converter for downstream).
    2. Use the O2 sensor socket to remove the faulty sensor.
    3. Install the new sensor and tighten it to the manufacturer’s specifications (typically around 30 lb-ft).
    4. Reconnect the electrical connector to the new sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• If the catalytic converter is found to be defective:
  • Tools Required: Socket set, jack and jack stands, exhaust hanger removal tool.
  • Sub-steps:
    1. Raise the vehicle using jack stands for safety.
    2. Disconnect any exhaust hangers using the exhaust hanger removal tool.
    3. Unbolt the catalytic converter from the exhaust pipes using the socket set.
    4. Install the new catalytic converter, ensuring proper alignment, and bolt it securely.
    5. Reattach the exhaust hangers.

4. Clear Codes and Test Drive

• After completing repairs:
  • Sub-steps:
    1. Reconnect the negative battery terminal.
    2. Use the OBD-II scanner to clear the P0420 code.
    3. Start the vehicle and allow it to reach operating temperature.
    4. Take the vehicle for a test drive to ensure the issue is resolved and the check engine light does not reappear.