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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, extension.
• Remove the upstream oxygen sensor by disconnecting the electrical connector and unscrewing it from the exhaust manifold.
• Replace it with a new oxygen sensor, ensuring it is properly tightened (usually 30-35 lb-ft).
• Repeat for the downstream sensor if it has shown signs of failure.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Wrench set, jack and jack stands, exhaust pipe cutter (if necessary), gasket scraper.
• Lift the vehicle using a jack and secure it with jack stands.
• Remove any heat shields or brackets securing the catalytic converter.
• Cut the exhaust pipes if necessary to remove the old catalytic converter.
• Install the new catalytic converter, ensuring all gaskets are in place and that it is properly aligned.
• Reattach any brackets or heat shields removed earlier.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the system.
• Start the engine and allow it to reach operating temperature.
• Conduct a test drive to ensure that the check engine light does not reappear.