how to fix my Ford Explorer Fifth Generation (2011-2019) check engine light code P0420

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the vehicle's battery to ensure safety.
• Tools Required: OBD-II scanner, multimeter, infrared thermometer, socket set, torque wrench.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors in the exhaust system.
2. Disconnect the electrical connectors from both sensors.
3. Remove the sensors using a socket or wrench.
4. Install the new sensors by threading them into the exhaust and tightening to the manufacturer's specifications (typically 30-40 ft-lbs).
5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Identify the catalytic converter location in the exhaust system.
2. Remove the exhaust pipes connected to the catalytic converter using a socket set.
3. Unbolt the catalytic converter from its mounting points.
4. Install the new catalytic converter, aligning it with the exhaust system.
5. Torque the bolts to manufacturer's specifications (generally around 30-35 ft-lbs).
6. Reattach the exhaust pipes and ensure all joints are sealed.

4. Reset the Check Engine Light

1. Reconnect the vehicle's battery.
2. Use the OBD-II scanner to clear the P0420 code from the ECU.
3. Start the engine and monitor for any reoccurrence of the check engine light.