how to fix P0420 code on my Ford F-150 Fourteenth Generation (2021-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical issues.
• Raise the vehicle securely on jack stands and ensure safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set
• Remove the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Inspect the sensors for any signs of damage or contamination.
• Replace any faulty sensors with new ones, ensuring they are properly torqued to manufacturer specifications.

3. Check and Repair Exhaust Leaks

• Inspect the exhaust manifold, pipes, and catalytic converter for cracks or holes.
• Use a smoke test to identify any leaks if necessary.
• Repair or replace damaged components as needed, ensuring all connections are airtight.

4. Test and Replace Catalytic Converter (if necessary)

• Tools Required: Wrench set, cutting tools (if necessary for removal)
• Measure the inlet and outlet temperatures of the catalytic converter; a significant difference indicates failure.
• If the converter is confirmed to be faulty, remove it by unbolting from the exhaust system.
• Install the new catalytic converter, ensuring proper alignment and torque to manufacturer specifications.

5. Reset the Engine Control Module (ECM)

• Reconnect the battery and use an OBD-II scanner to clear the P0420 code.
• Start the engine and let it reach operating temperature, then check for any reoccurring codes.