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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative terminal of the battery.
• Allow the engine to cool completely before working on it.

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 upstream oxygen sensor:
   • Use an oxygen sensor socket or a wrench to unscrew the sensor.
   • Disconnect the electrical connector.
3. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads (if recommended).
   • Screw in the new sensor and connect the electrical connector.
   • Torque specification: 30 lb-ft.
4. Remove the downstream oxygen sensor: Repeat the above steps for the downstream sensor.
5. Install the new downstream oxygen sensor: Follow the same procedure as above.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Inspect the catalytic converter: Look for any signs of physical damage or clogging.
2. Remove the catalytic converter:
   • Loosen the bolts on both ends of the catalytic converter using a socket set.
   • Carefully detach the converter from the exhaust system.
3. Install the new catalytic converter:
   • Align the new catalytic converter and secure it with bolts.
   • Torque specification: 40 lb-ft.
4. Reattach any exhaust hangers that were disconnected during removal.

4. Reset the Engine Control Unit (ECU)

1. Reconnect the negative battery terminal.
2. Use an OBD-II scanner to clear the P0420 code from the ECU.
3. Start the engine and let it idle for a few minutes to ensure everything is functioning properly.