how to fix P0420 code on Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the vehicle battery to ensure safety.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Safety goggles
• Gloves

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: The upstream sensor is before the catalytic converter, and the downstream sensor is after it.
2. Unplug the electrical connectors from both sensors.
3. Remove the sensors: Use a socket wrench to carefully unscrew the sensors from their mounts.
4. Install new oxygen sensors: Apply anti-seize compound to the threads of the new sensors and install them, tightening to the manufacturer's specifications (usually around 30 ft-lbs).
5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust heat shield: Unscrew any bolts holding the shield in place and set it aside.
2. Unbolt the catalytic converter: Use a socket wrench to remove the bolts connecting the converter to the exhaust pipe and engine manifold.
3. Inspect the old catalytic converter: Check for physical damage or excessive carbon buildup.
4. Install the new catalytic converter: Position it in place and secure it with bolts, tightening to the specified torque settings.
5. Reattach the exhaust heat shield.

4. Reset the Check Engine Light

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the P0420 code from the ECM.
3. Take the vehicle for a test drive to ensure that the check engine light does not reappear.