how to fix P0420 code on Honda CR-V Fifth Generation (2017-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is safely parked on a flat surface.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Use a wrench to disconnect the wiring harness from each sensor.
3. Remove the sensors using an O2 sensor socket.
4. Install the new oxygen sensors by reversing the removal steps. Ensure they are tightened to manufacturer specifications (typically around 30 lb-ft).
5. Reconnect the wiring harnesses securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove any heat shields or protective covers if present.
2. Disconnect the exhaust pipes from the catalytic converter using a socket set. Take care to support the exhaust system to prevent damage.
3. Remove the old catalytic converter. If it is welded, a cutting tool may be required.
4. Install the new catalytic converter, ensuring proper alignment with the exhaust pipes.
5. Torque the bolts to the manufacturer’s specifications to prevent leaks (typically around 25-35 lb-ft).
6. Reinstall any heat shields or protective covers.

4. Clear Codes and Test

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear any error codes from the ECU.
3. Start the engine and let it idle for a few minutes, then take the vehicle for a test drive to ensure the check engine light does not reappear.