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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to unscrew the sensors from the exhaust system.
  4. Install the new oxygen sensors by threading them into place and tightening them to the manufacturer's torque specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors to the new sensors.

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

• Tools Required: Socket set, torch (if bolts are rusted), exhaust hanger removal tool
• Sub-steps:
  1. Disconnect the exhaust pipes from the catalytic converter by removing the bolts/nuts using a socket set. If necessary, use a torch to loosen rusted bolts.
  2. Remove any mounting brackets or hangers securing the catalytic converter.
  3. Carefully remove the catalytic converter from the exhaust system.
  4. Install the new catalytic converter in place, ensuring proper alignment with exhaust pipes and brackets.
  5. Reattach the exhaust pipes and secure them tightly with bolts/nuts.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any stored trouble codes from the vehicle’s computer.