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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, jack stands, safety goggles, gloves.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use a socket wrench to remove the upstream oxygen sensor. If it is stuck, apply penetrating oil and wait a few minutes.
  3. Install the new upstream oxygen sensor and torque to the manufacturer's specifications (typically around 30-40 ft-lbs).
  4. Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Sub-steps:
  1. Raise the vehicle using jack stands and remove any heat shields that may obstruct access to the catalytic converter.
  2. Unbolt the catalytic converter from the exhaust system using a socket set, taking care to note the orientation for reinstallation.
  3. Inspect the catalytic converter for physical damage or clogging. If damaged, replace with an OEM or quality aftermarket unit.
  4. Install the new catalytic converter, ensuring all gaskets and bolts are replaced and torqued to manufacturer specifications (typically around 30-40 ft-lbs).
  5. Reinstall any removed heat shields.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and other stored codes.
• Start the engine and allow it to reach operating temperature.