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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  • Remove the upstream (pre-catalytic) oxygen sensor using an oxygen sensor socket.
  • Inspect the sensor for damage or contamination. Replace it if necessary.
  • Install the new oxygen sensor and torque to manufacturer's specifications (usually around 30 lb-ft).
  • Repeat for the downstream (post-catalytic) oxygen sensor if it has signs of failure or if the upstream sensor replacement did not resolve the code.

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  • If oxygen sensors are functioning properly, inspect the catalytic converter for damage or clogging.
  • If replacing, unbolt the catalytic converter from the exhaust system, taking care to support the exhaust system to prevent strain.
  • Install the new catalytic converter, ensuring proper alignment and sealing.
  • Torque the bolts to manufacturer's specifications (typically around 40-50 lb-ft).

4. Clear Codes and Test Drive

• Sub-steps:
  • Reconnect the battery.
  • Use the OBD-II scanner to clear the P0420 code from the engine computer.
  • Take the vehicle for a test drive under various conditions to verify that the check engine light does not reappear.