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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is turned off.
• Disconnect the battery by removing the negative terminal to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors

• 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 remove the upstream oxygen sensor.
  4. Install the new upstream sensor, tightening it to the manufacturer's specified torque (usually around 30 lb-ft).
  5. Repeat the removal and installation process for the downstream oxygen sensor if it's found to be faulty.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary), gasket scraper.
• Sub-steps:
  1. Inspect the catalytic converter for physical damage.
  2. If replacement is necessary, use an exhaust pipe cutter to remove the old catalytic converter.
  3. Clean the mating surfaces on the exhaust pipes using a gasket scraper.
  4. Install the new catalytic converter, ensuring all bolts are tightened to the specified torque (commonly around 40 lb-ft).
  5. Reconnect any heat shields or brackets that were removed.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other diagnostic trouble codes (DTCs).