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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery before starting work.
• Allow the exhaust system to cool down completely.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors:
   • The upstream sensor is typically located before the catalytic converter, and the downstream sensor is after it.
2. Remove the faulty oxygen sensor:
   • Use an oxygen sensor socket or wrench.
   • Disconnect the electrical connector and remove the sensor.
3. Install the new oxygen sensor:
   • Apply anti-seize compound on the threads of the new sensor (if recommended).
   • Tighten to the manufacturer's specification (usually 30-40 lb-ft).
   • Reconnect the electrical connector.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust pipe:
   • Use a socket set to remove bolts connecting the exhaust pipe to the catalytic converter.
   • Support the exhaust system to avoid strain.
2. Remove the old catalytic converter:
   • Detach any additional brackets or hangers securing the converter.
   • Note the orientation of the old converter for proper installation of the new one.
3. Install the new catalytic converter:
   • Position the new converter and secure it with bolts to the exhaust pipe.
   • Ensure all connections are tight and leak-free.

4. Reset the Engine Control Module (ECM)

1. Reconnect the battery after repairs.
2. Use an OBD-II scanner to clear the P0420 code from the ECM.
3. Perform a short test drive to monitor for any reoccurrence of the code.