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 the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter, socket set.
• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Use the multimeter to test the voltage output of both sensors while the engine is running.
  • Acceptable range: Upstream should fluctuate between 0.1 to 0.9 volts, while downstream should stabilize around 0.5 volts.
• If any sensor is out of range, replace it.

3. Inspect and Test the Catalytic Converter

• Tools Required: Exhaust gas temperature probe, jack stands.
• Lift the vehicle safely and access the catalytic converter.
• Inspect for physical damage such as dents or rust.
• Use an exhaust gas temperature probe to measure the temperature before and after the converter:
  • A significant temperature difference (more than 100°F) indicates a failing catalytic converter.
• If the converter is faulty, replace it.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.
• Take the vehicle for a test drive to monitor for any reoccurrence of the check engine light.