how to fix the P0420 code on my Ram 1500 DT (2019-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench, penetrating oil
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Use penetrating oil to loosen the sensors if they are rusted or stuck.
  3. Disconnect the electrical connectors from the sensors.
  4. Remove the sensors using the O2 sensor socket.
  5. Install the new sensors by threading them into place and tightening them to the manufacturer's specifications (typically around 30 ft-lbs).
  6. Reconnect the electrical connectors.

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

• Tools Required: Jack and jack stands, socket set, exhaust pipe cutter or saw, new gaskets, and bolts.
• Sub-steps:
  1. Raise the vehicle and secure it on jack stands.
  2. Locate the catalytic converter and the exhaust components connected to it.
  3. Use an exhaust pipe cutter or saw to cut the exhaust pipes if necessary.
  4. Remove the catalytic converter by unbolting it from the exhaust manifold and the downstream exhaust pipe.
  5. Install the new catalytic converter with new gaskets and bolts, tightening to the manufacturer's specifications (typically around 25 ft-lbs).
  6. Reconnect any exhaust components previously removed.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner
• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
  3. Start the engine and let it idle for a few minutes.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.