how to fix P0420 code Honda Accord 8th Generation (2008-2012)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to avoid electrical issues during repairs.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors (typically found before and after the catalytic converter).
2. Using an O2 sensor socket, carefully remove the upstream sensor and inspect it for contamination or damage.
3. If faulty, replace with a new oxygen sensor, ensuring it is properly torqued according to manufacturer specifications (usually around 30 ft-lbs).
4. Repeat the process for the downstream O2 sensor if necessary.

3. Inspect and Replace Catalytic Converter

1. If the catalytic converter is found to be damaged or clogged, it needs to be replaced.
2. Remove the exhaust pipe connected to the catalytic converter using a socket set.
3. Unbolt and remove the catalytic converter from its mounting.
4. Install the new catalytic converter in the reverse order of removal, ensuring all bolts are tightened to the manufacturer’s torque specifications (typically around 30-40 ft-lbs).
5. Reattach the exhaust pipe and ensure all connections are secure.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative terminal of the battery.
2. Start the engine and allow it to reach operating temperature.
3. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.