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

Solution

1. Preparation

• Gather all tools and parts needed for the repair.
• Disconnect the battery to ensure safety while working on electrical systems.
• Allow the engine to cool before starting any work on the exhaust system.

2. Inspect and Test Oxygen Sensors

• Remove the electrical connectors from both the upstream and downstream oxygen sensors.
• Use a multimeter to test the resistance of the sensors; replace if out of specification.
• Reconnect the sensors after testing or replace if necessary.

3. Inspect the Catalytic Converter

• If the sensors are functioning correctly, check the catalytic converter.
• Remove any heat shields and inspect for physical damage or signs of blockage.
• If the catalytic converter is damaged or clogged, remove it using the appropriate socket set.

4. Replace the Catalytic Converter (if necessary)

• Install the new catalytic converter by aligning it with the exhaust pipes.
• Secure it using new gaskets and bolts, tightening to the manufacturer's torque specifications (typically around 25-30 ft-lbs).
• Reinstall any heat shields removed during inspection.

5. Clear Error Codes

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code from the ECU.

6. Final Check

• Start the engine and let it idle for a few minutes.
• Check for leaks around the exhaust and ensure the engine runs smoothly.