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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to avoid any electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Apply penetrating oil on the sensor threads to ease removal.
  3. Disconnect the electrical connectors from both sensors.
  4. Use the O2 sensor socket to remove the sensors.
  5. Install the new sensors by reversing the removal steps, ensuring they are properly torqued (usually around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Disconnect the exhaust pipes connected to the catalytic converter by removing the bolts.
  3. Remove any heat shields or brackets securing the catalytic converter.
  4. Inspect the old catalytic converter for blockages or damage.
  5. Install the new catalytic converter, using a new exhaust gasket, and torque the bolts to the manufacturer's specifications (typically around 25 lb-ft).

4. Clear Diagnostic Codes

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s ECU.

5. Final Checks

• Sub-steps:
  1. Start the engine and let it idle for a few minutes.
  2. Check for any exhaust leaks around the newly installed components.