how to fix P0420 code on Honda CR-V Sixth Generation (2023-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the engine to cool before proceeding.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter, socket set
• Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Test each sensor's voltage output while the engine is running. The upstream sensor should fluctuate between 0.1 to 0.9 volts. If the readings are incorrect, replace the faulty sensor.

3. Check Catalytic Converter

• Tools Required: Exhaust backpressure gauge
• Remove the catalytic converter from the exhaust system.
• Perform a backpressure test by inserting the gauge into the exhaust pipe before the converter. A reading above 2.5 psi at idle indicates a clogged converter.
• If backpressure is excessive, replace the catalytic converter.

4. Reassemble and Reconnect

• Reinstall the oxygen sensors and catalytic converter.
• Ensure all fasteners are tightened to the manufacturer's torque specifications (typically around 30-40 ft-lbs for exhaust components).
• Reconnect the negative battery terminal.

5. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Conduct a test drive to ensure the vehicle operates normally and monitor for any reoccurrence of the code.