why is my Ford Explorer Fifth Generation (2011-2019) check engine light on with P0420 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use a socket wrench to disconnect the electrical connectors from both sensors.
3. Remove the oxygen sensors using an oxygen sensor socket.
4. Install new oxygen sensors, ensuring they are properly torqued according to manufacturer specifications (usually around 30 lb-ft).
5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Inspect the catalytic converter for physical damage or signs of clogging.
2. If replacement is needed, use a wrench to remove the bolts securing the catalytic converter to the exhaust system.
3. Carefully detach the catalytic converter from the exhaust pipe and any mounting brackets.
4. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
5. Torque the bolts to the manufacturer’s specifications (typically around 25-30 lb-ft).

4. Clear Error Codes

1. Reconnect the battery negative terminal.
2. Use the OBD-II scanner to clear the P0420 code and any other stored codes.
3. Start the vehicle and allow it to reach operating temperature.