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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Remove the upstream oxygen sensor:
  • Locate the upstream O2 sensor near the exhaust manifold.
  • Use the O2 sensor socket to unscrew and remove it.
• Test the sensor's voltage output:
  • Reconnect the sensor and start the engine.
  • Use a multimeter to check if the voltage fluctuates between 0.1V and 0.9V.
• If the sensor is faulty, replace it with a new one:
  • Apply anti-seize compound to the threads of the new sensor.
  • Install the new sensor and tighten it to the manufacturer’s specifications (usually around 30 Nm).
• Repeat the same process for the downstream oxygen sensor if needed.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust pipe cutter (if necessary).
• Raise the vehicle and secure it on jack stands.
• Remove any heat shields or brackets as required to access the catalytic converter.
• Inspect the catalytic converter for clogging or damage:
  • Tap it gently; if it rattles, the internal substrate may be broken.
• If replacement is needed, disconnect the exhaust pipes:
  • Cut the exhaust pipe if it's rusted or welded.
  • Remove the bolts securing the catalytic converter to the exhaust system.
• Install the new catalytic converter:
  • Align it with the exhaust pipes and secure it with new gaskets and bolts.
  • Tighten the bolts to the manufacturer’s specifications.

4. Reset the ECU

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