how to fix P0420 code on Ford F-150 13th Generation (2015-2020)

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, infrared thermometer, socket set, torque wrench, safety glasses, and gloves.
• Disconnect the negative battery terminal to prevent electrical shock and ensure safety during repairs.

2. Oxygen Sensor Inspection

• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Locate the upstream oxygen sensor in the exhaust manifold.
  2. Use a socket wrench to unscrew and remove the sensor.
• Test the oxygen sensor:
  1. Connect the multimeter to the sensor terminals according to the manufacturer's specifications.
  2. Start the engine and monitor the voltage output; it should fluctuate between 0.1 to 0.9 volts. Replace if faulty.

3. Catalytic Converter Assessment

• Check the catalytic converter:
  1. Use the infrared thermometer to measure the temperature at the inlet and outlet of the catalytic converter.
  2. The outlet temperature should be significantly higher than the inlet (typically a difference of around 100°F is expected). If not, the catalytic converter may be clogged.
• Replace the catalytic converter:
  1. If necessary, unbolt the catalytic converter from the exhaust system using a socket set.
  2. Install the new catalytic converter, ensuring proper alignment with exhaust hangers and flanges.
  3. Torque the bolts to the manufacturer's specifications (usually around 30-40 lb-ft).

4. Reinstall Oxygen Sensors

• Reinstall the upstream and downstream oxygen sensors:
  1. Apply anti-seize compound to the threads of the new oxygen sensors.
  2. Screw them into place and tighten to the manufacturer's torque specifications (typically 30 lb-ft).

5. Final Steps

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.