how to fix Ram 1500 DT (2019-Present) check engine light P0420 code

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Apply penetrating oil to the sensor threads and let it sit for a few minutes.
  3. Use the O2 sensor socket to remove the upstream sensor first, followed by the downstream sensor.
  4. Install the new oxygen sensors and torque to manufacturer specifications (usually around 30 ft-lbs).

3. Inspect and Repair Exhaust System

• Tools Required: Socket set, exhaust clamp tool, jack stands.
• Sub-steps:
  1. Lift the vehicle and secure it with jack stands.
  2. Visually inspect the entire exhaust system for leaks, rust, or damage.
  3. If leaks are found, repair or replace sections of the exhaust using clamps or new piping as needed.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust gasket, torque wrench.
• Sub-steps:
  1. Locate the catalytic converter and disconnect any exhaust hangers or brackets.
  2. Remove bolts connecting the catalytic converter to the exhaust system.
  3. Install the new catalytic converter with a new gasket and torque bolts to manufacturer specifications.
  4. Reattach any hangers or brackets.

5. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 error code and any other related codes.