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 prevent electrical shorts.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Apply penetrating oil to the sensor threads and allow it to sit for a few minutes.
• Remove both oxygen sensors using the O2 sensor socket.
• Install the new oxygen sensors and torque to the manufacturer specification (typically around 30 lb-ft).
• Reconnect electrical connectors.

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

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Remove the exhaust pipe connected to the catalytic converter by loosening the clamps and bolts.
• Carefully take out the catalytic converter, ensuring no damage is done to surrounding components.
• Compare the old catalytic converter with the new one to ensure compatibility.
• Install the new catalytic converter, using new gaskets as necessary, and torque to manufacturer specifications (typically around 40-50 lb-ft).
• Reattach the exhaust pipe and secure with clamps.

4. Reset the Engine Control Module (ECM)

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