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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts during the repair process.
• Ensure the vehicle is on a flat surface and securely lifted if necessary.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the sensors: Use an oxygen sensor socket to carefully unscrew and remove both sensors.
3. Inspect the sensors: Check for any visible damage, corrosion, or contamination.
4. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them, tightening to manufacturer specifications (usually around 30 ft-lbs).
5. Reconnect wiring: Ensure the wiring harnesses are securely connected.

3. Inspect and Replace the Catalytic Converter

1. Remove the exhaust components: Depending on your configuration, you may need to remove heat shields or exhaust pipes attached to the catalytic converter using a socket set.
2. Check for damage: Inspect the converter for physical damage or signs of clogging.
3. Install a new catalytic converter: Position the new catalytic converter in place, ensuring all gaskets are replaced to prevent leaks.
4. Secure connections: Tighten all bolts to manufacturer specifications.
5. Reinstall any removed components: If any exhaust components or heat shields were removed, reinstall them.

4. Reset the ECU

1. Reconnect the battery: Reconnect the negative battery terminal.
2. Clear the error codes: Use the OBD-II scanner to clear the P0420 code from the ECU.