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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Inspect the sensors for damage or contamination.
• Replace any faulty oxygen sensors with OEM or high-quality aftermarket parts.
• Torque the new sensors to the manufacturer's specifications (typically around 30-40 lb-ft).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter (if needed), gasket scraper, torque wrench.
• Remove the exhaust pipes connected to the catalytic converter.
• Carefully detach the catalytic converter from the exhaust manifold and downstream pipe.
• Inspect the catalytic converter for physical damage or clogging.
• If defective, replace the catalytic converter with a new unit that meets OEM specifications.
• Install the new catalytic converter using new gaskets and secure with bolts, torquing to the manufacturer’s specifications.

4. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to ensure the check engine light does not reappear.