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

Solution

1. Preparation

• Gather tools and materials.
• Disconnect the negative battery terminal.
• Raise the vehicle safely using jack stands.

2. Inspect Exhaust System

• Tools Required: Visual inspection tools, flashlight.
• Inspect the entire exhaust system for leaks, especially near the catalytic converter and connections.
• Tighten any loose clamps or bolts and replace any damaged sections of the exhaust.

3. Check Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter, socket set.
• Remove the upstream and downstream oxygen sensors using the appropriate socket.
• Check the electrical connections for corrosion or damage.
• Use a multimeter to test the voltage output while the engine is running; the upstream sensor should oscillate between 0.1V to 0.9V.

4. Replace Oxygen Sensors (if faulty)

• If any sensor is not functioning correctly, replace it with a new one.
• Installation Steps:
  • Apply anti-seize compound to the threads of the new sensor.
  • Install the new sensor and tighten it to the manufacturer's specifications (typically around 30 lb-ft).
  • Reconnect the electrical connector.

5. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket.
• If the catalytic converter is damaged or clogged, replace it.
• Remove any heat shields, then disconnect the catalytic converter from the exhaust system.
• Replace with a new catalytic converter, ensuring proper alignment and sealing with a new gasket.
• Torque the bolts to the manufacturer's specifications (consult service manual for exact torque values).

6. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Conduct a test drive to ensure the issue is resolved and that the check engine light does not reappear.