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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, penetrating oil.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Apply penetrating oil to the sensor threads and allow it to sit for a few minutes.
  3. Disconnect the electrical connectors from both oxygen sensors.
  4. Use the O2 sensor socket to carefully remove the sensors from their respective locations.
  5. Install new oxygen sensors in the reverse order, ensuring they are properly torqued (typically 30 lb-ft) and reattach the electrical connectors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, cutting torch (if necessary), exhaust clamps.
• Sub-steps:
  1. Inspect the catalytic converter for physical damage or blockage.
  2. If replacement is necessary, carefully unbolt or cut the old catalytic converter from the exhaust system.
  3. Install the new catalytic converter, ensuring proper alignment and securing bolts to the specified torque (consult service manual for values).
  4. Use new exhaust clamps to secure connections where applicable.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear any diagnostic trouble codes from the vehicle’s computer.
  3. Start the vehicle and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear and monitor for performance issues.