how to fix Honda Civic 10th Generation (2016-2021) P0420 code

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Use a socket wrench to remove the upstream oxygen sensor.
3. Inspect the sensor for damage and replace it if necessary.
4. Repeat the process for the downstream oxygen sensor.

Tools Required:

• OBD-II scanner
• Socket set (including oxygen sensor socket)
• Multimeter
• Wrench set

3. Inspect and Replace Catalytic Converter

1. If oxygen sensors are functioning properly, inspect the catalytic converter.
2. Remove the exhaust pipe connected to the catalytic converter using a socket set.
3. Unbolt the catalytic converter from the exhaust manifold and remove it.
4. Install the new catalytic converter and secure it with the bolts. Ensure proper alignment.
5. Reconnect the exhaust pipe and tighten all bolts to the specified torque (usually around 25-30 lb-ft).

Parts Required:

• Upstream oxygen sensor
• Downstream oxygen sensor
• Catalytic converter