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

Solution

1. Preparation

• Tools Needed: OBD-II scanner, multimeter, temperature probe, socket set, jack and jack stands.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before working on the exhaust system.

2. Inspect Exhaust System

• Sub-steps:
  • Raise the vehicle using a jack and secure it with jack stands.
  • Visually inspect the exhaust manifold, pipes, and catalytic converter for any signs of damage or leaks.
  • If leaks are found, repair or replace the affected sections.

3. Test Oxygen Sensors

• Sub-steps:
  • Locate the front and rear oxygen sensors on the exhaust system.
  • Disconnect the sensors' electrical connectors.
  • Use a multimeter to measure the voltage output of each sensor while the engine is running. The front sensor should fluctuate between 0.1 to 0.9 volts; the rear sensor should be relatively stable.
  • If either sensor is faulty, replace it.

4. Replace Catalytic Converter (if necessary)

• Sub-steps:
  • If the catalytic converter is determined to be faulty, remove it by:
    • Unbolting the exhaust flange connections.
    • Disconnecting any oxygen sensors attached to the catalytic converter.
  • Install the new catalytic converter by reversing the removal steps, ensuring all bolts are tightened to the manufacturer's specified torque.
  • Reconnect any oxygen sensors and electrical connectors.

5. Reset the Check Engine Light

• Sub-steps:
  • Reconnect the negative battery terminal.
  • Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  • Start the engine and let it idle for a few minutes.