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 any electrical issues during repair.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter.
• Remove the upstream and downstream oxygen sensors using a socket wrench.
• Clean the sensor connectors and inspect the wiring for damage.
• Test the sensors' operation using a multimeter; replace any faulty sensors.

3. Check Catalytic Converter

• Tools Required: Exhaust backpressure gauge.
• Remove the catalytic converter from the exhaust system.
• Use the backpressure gauge in the exhaust pipe to measure the pressure; it should not exceed 1.5 psi at 2,500 RPM.
• If backpressure is high, replace the catalytic converter.

4. Repair Exhaust Leaks

• Tools Required: Exhaust sealant, wrenches.
• Inspect the exhaust system for leaks, particularly around flanges and joints.
• Use exhaust sealant or replace gaskets as needed to seal leaks properly.

5. Reinstall Components

• Reinstall the catalytic converter and oxygen sensors in reverse order of removal.
• Ensure all connections are tight and gaskets are properly seated.

6. Reset the Engine Control Module (ECM)

• Tools Required: OBD-II scanner.
• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the ECM.