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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical components.
• Raise the vehicle using a jack and secure with jack stands if necessary.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Use an oxygen sensor socket to remove the sensors carefully.
3. Inspect the sensors for damage or corrosion.
4. If faulty, install new oxygen sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Torque the sensors to the manufacturer’s specifications (usually around 30 ft-lbs).
5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

1. Visually inspect the catalytic converter for signs of damage or blockage.
2. If replacement is needed, unbolt the catalytic converter from the exhaust system:
   • Use a socket set to remove bolts and clamps, taking care to avoid damaging surrounding components.
3. Install the new catalytic converter:
   • Position the converter and secure it with new gaskets (if required).
   • Torque the bolts to manufacturer specifications.
4. Reconnect any necessary exhaust components.

4. Reset the Engine Control Module (ECM)

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the trouble codes from the ECM.
3. Start the engine and allow it to reach operating temperature.