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

Solution

1. Preparation

• Gather necessary tools and parts.
• Make sure the vehicle is parked on a level surface and the ignition is off.
• Disconnect the battery to ensure safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter
• Remove the upstream oxygen sensor:
  1. Locate the upstream O2 sensor (before the catalytic converter).
  2. Use an O2 sensor socket to carefully unscrew the sensor.
  3. Inspect the sensor for damage or contamination.
  4. If faulty, install the new sensor and torque to manufacturer specifications (typically around 30 lb-ft).
• Repeat steps for the downstream O2 sensor (after the catalytic converter).

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

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed)
• To replace the catalytic converter:
  1. Raise the vehicle securely on jack stands.
  2. Remove the exhaust system components before the catalytic converter, noting the order for reassembly.
  3. Inspect the catalytic converter for damage or clogging.
  4. If damaged, unbolt the catalytic converter from the exhaust pipes and remove it.
  5. Install the new catalytic converter and secure it with bolts, torquing to manufacturer specifications.
  6. Reassemble the exhaust components in reverse order.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code.
• Test drive the vehicle for at least 30 minutes to ensure the code does not return.