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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the vehicle to cool down if the engine has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Inspect the upstream and downstream oxygen sensors for damage or corrosion.
• If faulty, remove the old oxygen sensors:
  1. Use the O2 sensor socket to unscrew the upstream sensor from the exhaust manifold.
  2. Repeat for the downstream sensor located before the catalytic converter.
• Install new oxygen sensors:
  1. Apply anti-seize compound to the threads of the new sensors.
  2. Screw in the new sensors by hand, then tighten to the manufacturer’s specifications (typically around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust wrench
• If the catalytic converter is suspected to be faulty:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Disconnect the exhaust pipes from the catalytic converter using an exhaust wrench.
  3. Remove the catalytic converter from its mounting brackets.
  4. Install the new catalytic converter and secure it with the original or new mounting hardware.
  5. Reconnect the exhaust pipes and ensure all connections are tight.

4. Clear Codes and Test

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