how to fix P0420 code in Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down if the engine has been running.

2. Inspect and Replace Oxygen Sensors

Tools Required:

• O2 sensor socket
• Ratchet and extension

Steps:

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use the O2 sensor socket to remove the upstream sensor.
3. Install the new upstream oxygen sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
4. Repeat the process for the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter

Tools Required:

• Socket set
• Torque wrench
• Exhaust pipe cutter (if necessary)

Steps:

1. Inspect the catalytic converter for any physical damage or excessive heat discoloration.
2. If replacement is needed, remove the exhaust pipes connected to the catalytic converter using the socket set.
3. If necessary, use the exhaust pipe cutter to remove the old catalytic converter.
4. Install the new catalytic converter, ensuring proper alignment.
5. Tighten all bolts to the specified torque (typically around 30-40 ft-lbs).

4. Clear Codes and Test

Tools Required:

• OBD-II scanner

Steps:

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code.
3. Start the engine and allow it to reach operating temperature.
4. Take the vehicle for a test drive to ensure that the check engine light does not return.