how to fix P0420 issue on Ford Explorer Sixth Generation (2020-present) effectively?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the electrical components.
• Raise the vehicle on jack stands for safe access to the undercarriage.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • Unplug the electrical connectors for both sensors.
  • Use a socket wrench to remove the old sensors.
  • Apply anti-seize compound to the threads of the new sensors.
  • Install the new oxygen sensors and reconnect the electrical connectors.

3. Test and Replace Catalytic Converter (if necessary)

• Sub-steps:
  • Perform a backpressure test on the catalytic converter through the O2 sensor hole or by using a pressure gauge.
  • If the readings exceed manufacturer specifications (generally above 2.5 psi at 2500 RPM), the catalytic converter may be clogged.
  • Remove the exhaust components connected to the catalytic converter by unbolting and disconnecting any hangers.
  • Install the new catalytic converter in reverse order of removal, ensuring all gaskets are in place and the bolts are torqued to specification (typically 20-30 lb-ft).

4. Reset the Engine Control Module (ECM)

• Sub-steps:
  • Reconnect the battery.
  • Use the OBD-II scanner to clear any trouble codes from the ECM.
  • Start the vehicle and allow it to reach operating temperature.