how to fix P0420 code on my Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, safety goggles, gloves.
• Safety Warnings: Disconnect the battery before working on electrical systems; allow the engine to cool before opening the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Disconnect the electrical connectors from both sensors.
3. Remove the sensors using a socket wrench.
4. Install the new oxygen sensors and torque them to the manufacturer's specifications (usually around 30-40 ft-lbs).
5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Raise the vehicle using a jack and secure it with jack stands.
2. Locate the catalytic converter and inspect it for physical damage or blockages.
3. If replacement is needed, unbolt the catalytic converter from the exhaust system using a socket set.
4. Install the new catalytic converter, ensuring proper alignment with the exhaust pipes.
5. Torque the bolts to the manufacturer's specifications (typically around 30-40 ft-lbs).
6. Reconnect any oxygen sensors if they were removed during the process.

4. Clear the Check Engine Light

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