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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands.
• Disconnect the vehicle's battery to ensure safety while working on the electrical components.

2. Inspect and Repair Exhaust System

• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Visually inspect the exhaust system from the engine to the tailpipe for any cracks or leaks.
  3. Use exhaust sealant or replace any damaged sections if leaks are found.

3. Test and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Using a multimeter, measure the voltage output of the upstream sensor while the engine is running; it should fluctuate between 0.1V and 0.9V.
  3. Repeat the measurement for the downstream sensor; it should be steady, typically around 0.5V.
  4. If either sensor is faulty, disconnect the sensor's electrical connector and use a socket to remove the sensor.
  5. Install a new oxygen sensor and reconnect the electrical connector.

4. Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. If the catalytic converter is confirmed to be damaged or contaminated, prepare to replace it.
  2. Remove the bolts securing the catalytic converter to the exhaust system using a socket set.
  3. Carefully detach the catalytic converter from the exhaust pipes and replace it with a new unit.
  4. Torque the bolts to the manufacturer’s specifications, generally around 30-50 lb-ft.

5. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery and use the OBD-II scanner to clear the P0420 code from the memory.