how do I fix P0420 code in my Ford Explorer Fifth Generation (2011-2019)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Apply penetrating oil to the sensor threads to ease removal.
  3. Disconnect the electrical connectors from both sensors.
  4. Use the O2 sensor socket to remove the sensors from the exhaust.
  5. Install new oxygen sensors by reversing the removal procedure, ensuring they are tightened to 30 Nm (22 lb-ft).

3. Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter or saw, gaskets.
• Sub-steps:
  1. Use an exhaust pipe cutter or saw to cut the exhaust pipes on either side of the catalytic converter.
  2. Remove the old catalytic converter from the exhaust system.
  3. Clean the mating surfaces on the exhaust pipes to ensure a good seal.
  4. Install the new catalytic converter, ensuring the correct orientation.
  5. Use new gaskets and tighten the bolts to the manufacturer's specifications (typically around 40 Nm or 30 lb-ft).

4. Reconnect Battery

• Reconnect the negative battery terminal once all repairs are complete.