how to fix P0420 code on Honda Pilot YF4 (2023-Present)

Solution

1. Preparation

• Gather necessary tools and safety equipment.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle on jack stands and ensure it is secure.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Check the voltage of the upstream oxygen sensor while the engine is running. It should fluctuate between 0.1V and 0.9V.
• Perform the same test on the downstream sensor; it should be more stable, indicating a less variable reading.

3. Replace Faulty Oxygen Sensors (if necessary)

• Tools Required: Wrench set, oxygen sensor socket
• Locate the upstream and downstream oxygen sensors.
• Disconnect the wiring harness and use the oxygen sensor socket to remove the faulty sensor.
• Install the new sensor and reconnect the wiring harness, ensuring it's secure.

4. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, gasket scraper, jack, and jack stands
• Locate the catalytic converter and inspect for physical damage or blockages.
• If replacement is needed, unbolt the old catalytic converter and remove it.
• Clean the exhaust manifold and exhaust pipe mating surfaces with a gasket scraper.
• Install the new catalytic converter, ensuring all bolts are torqued to manufacturer specifications.

5. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.