how to fix P0420 code on Ford Explorer Fifth Generation (2011-2019)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

1. Locate Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove Sensors:
   • Use an oxygen sensor socket to unscrew the sensors from the exhaust manifold and catalytic converter.
   • Be careful to avoid damaging the wiring.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Thread the new sensors into place and torque to the manufacturer’s specifications (typically around 30 lb-ft).
4. Reconnect Wiring: Ensure electrical connectors are secure.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Visual Inspection: Check for any physical damage or signs of excessive heat on the catalytic converter.
2. Temperature Test: Start the engine and let it reach operating temperature. Use an infrared thermometer to compare inlet and outlet temperatures; a significant difference indicates a clogged converter.
3. Remove Old Catalytic Converter:
   • Loosen and remove the bolts connecting the catalytic converter to the exhaust.
   • Carefully detach the converter from the exhaust system.
4. Install New Catalytic Converter:
   • Position the new catalytic converter and secure it with bolts.
   • Torque bolts to manufacturer specifications (consult repair manual for exact values).

4. Clear Codes and Test Drive

1. Reconnect Battery: Reconnect the negative battery terminal.
2. Clear codes: Use the OBD-II scanner to clear the P0420 code.
3. Test Drive: Drive the vehicle under various conditions to ensure the check engine light does not return.