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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool down before working.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Check the upstream oxygen sensor for proper voltage output (should fluctuate between 0.1V and 0.9V during operation).
• Check the downstream oxygen sensor; it should have a more stable voltage output (around 0.5V to 0.7V).
• If either sensor is faulty, replace as needed.

3. Inspect Catalytic Converter

• Tools Required: Socket set, jack stands
• Raise the vehicle and support it securely on jack stands.
• Inspect the catalytic converter for signs of damage, such as dents or rust.
• If it appears clogged or damaged, proceed to replace it.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust gasket
• Remove any bolts or clamps securing the catalytic converter to the exhaust system.
• Carefully detach the catalytic converter from the exhaust pipe.
• Install the new catalytic converter, ensuring to use a new gasket for a proper seal.
• Torque the bolts to the manufacturer’s specifications (typically around 30-40 lb-ft, but refer to the service manual for exact values).

5. Clear Codes and Recheck

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any fault codes.
• Start the engine and allow it to reach operating temperature.