how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface, turn off the ignition, and set the parking brake.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, OBD-II scanner.
• Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) O2 sensors.
• Using the O2 sensor socket, carefully remove the upstream sensor first.
• Install the new upstream O2 sensor by screwing it in place and tightening it to the manufacturer's torque specifications (typically 30-40 Nm).
• Repeat the process for the downstream O2 sensor if necessary. Replace it if it shows signs of failure or if the temperature check indicated a malfunction.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust sealant (if required).
• Locate the catalytic converter under the vehicle.
• Inspect for physical damage or blockage. If damaged, proceed to replace it.
• Remove the exhaust bolts connecting the catalytic converter to the exhaust manifold and the exhaust pipe using a socket set.
• Carefully remove the old catalytic converter.
• Install the new catalytic converter, ensuring proper alignment with the exhaust system.
• Tighten the bolts to the manufacturer's torque specifications (usually around 25-30 Nm).
• If necessary, apply exhaust sealant to prevent leaks.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Start the engine and let it idle for a few minutes.
• Use the OBD-II scanner to clear the P0420 code from the system.