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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor by using an O2 sensor socket.
• Inspect the sensor for damage or excessive carbon buildup.
• If damaged, replace it with a new sensor, tightening it to manufacturer's specifications (typically around 30 ft-lbs).
• Repeat the process for the downstream oxygen sensor if required.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary)
• Remove the bolts connecting the catalytic converter to the exhaust manifold and the exhaust pipe.
• Inspect the catalytic converter for signs of damage or blockage.
• If replacement is needed, install a new catalytic converter, ensuring all connections are secure and torqued to specifications.
• Reconnect any exhaust hangers and ensure the system is leak-free.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any fault codes from the ECU.
• Test drive the vehicle for at least 20 minutes to allow the ECU to re-evaluate the catalytic converter's performance.