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 parked on a level surface and engage the parking brake.
• Disconnect the battery's negative terminal to prevent electrical shorts.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the upstream and downstream oxygen sensors using a socket wrench.
• Using a multimeter, test the voltage output of both sensors:
  • Upstream should fluctuate between 0.1V and 0.9V.
  • Downstream should remain relatively stable around 0.5V.
• If the readings are outside normal ranges, replace the faulty sensor.

3. Check Exhaust System

• Tools Required: Socket set, jack stands
• Raise the vehicle securely using jack stands.
• Inspect the exhaust pipes for any visible holes or rust.
• If leaks are found, replace affected sections of the exhaust or use exhaust repair tape as a temporary solution.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, gaskets
• If the catalytic converter is deemed faulty, remove the old unit by:
  • Disconnecting any heat shields or brackets holding it in place.
  • Unbolting the catalytic converter from the exhaust system using a socket set.
• Install the new catalytic converter:
  • Ensure all gaskets are replaced.
  • Torque all bolts to the manufacturer's specifications (typically around 30-35 lb-ft, but refer to service manual for specific values).

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECM.
• Start the engine and allow it to reach operating temperature.