how to fix P0420 code on Ford Explorer Fifth Generation (2011-2019)

Solution

1. Preparation

• Gather all necessary tools and parts before starting the repair.
• Disconnect the vehicle’s battery to prevent electrical issues during repairs.

2. Oxygen Sensor Replacement

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually found before and after the catalytic converter).
  2. Apply penetrating oil to the sensor threads and wait a few minutes for it to soak.
  3. Disconnect the electrical connector from the oxygen sensor.
  4. Use the O2 sensor socket to remove the faulty sensor by turning it counterclockwise.
  5. Install the new sensor by threading it in and tightening it to the manufacturer’s specified torque (typically around 30 lb-ft).
  6. Reconnect the electrical connector.

3. Catalytic Converter Inspection/Replacement

• Tools Required: Socket set, torque wrench, exhaust clamp tool.
• Sub-steps:
  1. If the catalytic converter is damaged or clogged, remove the exhaust pipes connected to it using the socket set.
  2. Remove any mounting bolts or clamps securing the catalytic converter in place.
  3. Inspect the old catalytic converter for internal damage or blockage (rattling sounds may indicate failure).
  4. Install the new catalytic converter, ensuring it is seated correctly.
  5. Secure it with the mounting bolts/clamps and tighten to the manufacturer’s specified torque.
  6. Reconnect the exhaust system components.

4. Final Checks

• Reconnect the battery.
• Clear the check engine codes using an OBD-II scanner.
• Start the engine and let it reach operating temperature while monitoring for leaks.