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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the vehicle is parked on a flat surface and secure it with wheel chocks.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Use an O2 sensor socket and remove both sensors.
3. Inspect the sensors for damage or excessive carbon build-up.
4. Replace with new OEM or quality aftermarket oxygen sensors.
5. Torque the sensors to manufacturer specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

1. Visually inspect the catalytic converter for any signs of physical damage or excessive carbon build-up.
2. If replacement is required, loosen and remove exhaust clamps and bolts securing the catalytic converter.
3. Remove the old catalytic converter from the exhaust system.
4. Install the new catalytic converter, ensuring a proper fit and alignment.
5. Reattach exhaust clamps and bolts, torquing to manufacturer specifications.

4. Clear Codes and Test

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the P0420 code from the ECM.
3. Start the vehicle and allow it to reach operating temperature.
4. Take the vehicle for a test drive to ensure proper operation and check if the check engine light returns.