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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, jack and jack stands, safety goggles, gloves.
• Clear the P0420 code using the OBD-II scanner.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Find the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the Battery: Disconnect the negative terminal to prevent electrical short circuits.
3. Remove the Sensors: Use the appropriate socket to unbolt the oxygen sensors, taking care not to damage the wiring.
4. Inspect the Wiring: Check the wiring for any signs of wear or damage, and repair as necessary.
5. Install New Sensors: If replacement is needed, install the new sensors by reversing the removal steps and ensuring they are torqued to the manufacturer's specifications (usually around 30-40 ft-lbs).

3. Inspect and Replace Catalytic Converter

1. Check for Clogs: Use a backpressure gauge to check for clogs in the catalytic converter.
2. Remove the Exhaust Pipe: Unbolt the exhaust pipe from the catalytic converter using a socket set.
3. Remove the Catalytic Converter: Unbolt the catalytic converter from the exhaust manifold.
4. Install New Catalytic Converter: Position the new catalytic converter and bolt it in place, following manufacturer torque specifications (typically 30-40 ft-lbs for exhaust bolts).
5. Reattach the Exhaust Pipe: Secure the exhaust pipe back to the catalytic converter.

4. Final Checks

1. Reconnect the Battery: Reconnect the negative battery terminal.
2. Clear Codes Again: Use the OBD-II scanner to clear any error codes.
3. Test Drive: Drive the vehicle for a short distance to allow the system to recalibrate and monitor for any new codes.