my Ram 1500 DT (2019-Present) has a check engine light with code P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety.
• Allow the exhaust system to cool down before starting.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet with extensions, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Using the O2 sensor socket, remove the upstream sensor first, followed by the downstream sensor.
  4. Install the new oxygen sensors, tightening them to the manufacturer’s specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting torch or saw (if welding is required), exhaust clamps.
• Sub-steps:
  1. Remove the bolts connecting the catalytic converter to the exhaust system using a socket wrench.
  2. If the converter is welded in place, carefully cut it out using a cutting torch or saw.
  3. Install the new catalytic converter, ensuring it is oriented correctly and secured with bolts or exhaust clamps.
  4. Reconnect any oxygen sensors if they were removed.

4. Reconnect Battery

• Reconnect the battery terminal securely.

5. Clear Error Codes

• Use an OBD-II scanner to clear the P0420 code from the vehicle’s computer.