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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands, safety glasses, gloves.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery before working on electrical systems.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use a socket wrench to carefully remove the oxygen sensors.
  3. Inspect the sensors for any signs of damage or contamination.
  4. If faulty, replace with OEM or high-quality aftermarket sensors, ensuring proper fit.
  5. Torque the new sensors to the manufacturer’s specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for physical damage, rust, or rattling.
  2. If replacement is needed, unbolt the exhaust pipes connected to the converter.
  3. Remove any mounting brackets or hangers securing the converter.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque all bolts to manufacturer specifications (usually around 40-50 ft-lbs).
  6. Reconnect any sensors or hoses that were removed.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.