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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, multimeter
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Disconnect the electrical connector.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
• Check the resistance using a multimeter; replace if it’s out of specification.
• Install the new upstream oxygen sensor, tightening to the manufacturer's torque specification (usually around 30 ft-lbs).
• Repeat the process for the downstream (post-catalytic) oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter, torque wrench
• Check for physical damage:
  1. Inspect the catalytic converter for dents, cracks, or excessive rust.
  2. If damaged, proceed to replace the converter.
• Remove the old catalytic converter:
  1. Unbolt the exhaust flanges.
  2. Use the exhaust pipe cutter to separate the converter from the exhaust pipe if needed.
• Install the new catalytic converter:
  1. Position the new converter and align it with the exhaust system.
  2. Secure it with new gaskets and bolts, tightening to the manufacturer's specifications.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
• Reconnect the battery and use the OBD-II scanner to clear any fault codes.
• Test drive the vehicle for a minimum of 20 miles to ensure the check engine light does not reappear.