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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the vehicle to cool if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.

• Remove the upstream (pre-catalytic) oxygen sensor using the O2 sensor socket.

  • Sub-steps:
    • Locate the sensor on the exhaust manifold.
    • Disconnect the wiring harness carefully.
    • Use the O2 sensor socket to unscrew the sensor.

• Install the new upstream oxygen sensor.

  • Sub-steps:
    • Apply anti-seize compound to the threads if required.
    • Torque to manufacturer specifications (typically around 30 lb-ft).
    • Reconnect the wiring harness.

• Repeat the process for the downstream oxygen sensor if faulty.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, cutting tools (if necessary).
• Remove the exhaust system components surrounding the catalytic converter if needed for access.
  • Sub-steps:
    • Loosen and remove any bolts or clamps securing the exhaust.
    • Carefully detach the catalytic converter from the exhaust system.
• Inspect the catalytic converter for damage or blockage.
• Install the new catalytic converter.
  • Sub-steps:
    • Position the new converter in place.
    • Secure with bolts, tightening them to the specified torque (typically around 25 lb-ft).
    • Reattach any exhaust components removed during the process.

4. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the stored P0420 code.
• Start the engine and allow it to reach operating temperature.