how to troubleshoot Ford Explorer Sixth Generation (2020-present) P0420 code

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the vehicle to cool down if the engine was running.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Test the sensors using a multimeter:
  • Set to voltage mode and observe the output voltage while the engine is running.
  • Upstream sensor should fluctuate between 0.1 and 0.9 volts.
• Replace any faulty sensors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack stands, exhaust pipe cutter (if necessary)
• Raise the vehicle using jack stands.
• Remove the exhaust pipe clamps connecting the catalytic converter to the exhaust system.
• If necessary, cut the exhaust pipe to detach the catalytic converter.
• Inspect for any visible blockages or physical damage to the catalytic converter.
• Replace with a new catalytic converter if damaged or blocked.

4. Reinstall Components

• Reinstall the catalytic converter and secure it with clamps.
• Reinstall the oxygen sensors and ensure they are tightened to manufacturer specifications.
• Reconnect the negative battery terminal.

5. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Test drive the vehicle for a minimum of 20 miles under various conditions.