how to diagnose the P0420 error code on my Honda CR-V Sixth Generation (2023-present)

Solution

1. Preparation

• Gather tools and parts required.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts during the repair.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set
• Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Inspect the sensors for carbon buildup or damage.
• If faulty, replace with OEM or high-quality aftermarket sensors.
• Reinstall the sensors and reconnect the electrical connectors.

3. Clean or Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter (if needed), gasket scraper
• If the catalytic converter is confirmed to be clogged or damaged, remove it from the exhaust system.
• Inspect the mounting hardware and replace if corroded.
• If cleaning, use a suitable catalytic converter cleaner and follow the manufacturer's instructions.
• If replacing, install the new catalytic converter ensuring all connections are tight and leak-free, using new gaskets as necessary.

4. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Reconnect the battery if it was disconnected in the preparation step.