my Ram 1500 DT (2019-Present) is showing P0420, how do I fix it?

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
• Locate the upstream and downstream oxygen sensors.
• Apply penetrating oil to the sensor threads to ease removal.
• Disconnect the electrical connectors from both sensors.
• Use the O2 sensor socket to remove the sensors.
• Install new oxygen sensors, tightening to the manufacturer’s specified torque.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter or saw.
• Raise the vehicle securely on jack stands.
• Inspect the catalytic converter for damage or blockage. If damaged, proceed to replacement.
• Remove any heat shields or components obstructing access to the catalytic converter.
• Use the exhaust pipe cutter or saw to remove the old catalytic converter.
• Install the new catalytic converter, ensuring all connections are tight and secure.
• Reattach any heat shields or components removed during the process.

4. Reconnect Battery and Test

• Reconnect the battery terminals securely.
• Start the engine and let it idle for a few minutes to ensure proper operation.
• Use the OBD-II scanner to check for any new trouble codes.