my Ram 1500 DT (2019-Present) check engine light came on with code P0420

Solution

1. Preparation

• Gather tools and parts required for repair.
• Disconnect the vehicle's battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

1. Remove the oxygen sensors: Use a socket wrench to unscrew the upstream and downstream oxygen sensors from the exhaust pipes.
2. Inspect the sensors: Check for any signs of wear or contamination on the sensor tips. If the sensors are damaged or have excessive buildup, they should be replaced.
3. Install new sensors: Apply anti-seize compound to the threads and install new oxygen sensors, tightening them to the manufacturer's specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust system components: Using a socket set, unbolt the catalytic converter from the exhaust piping. Be cautious to support the exhaust system to prevent damage.
2. Inspect the catalytic converter: Look for physical damage or signs of clogging. A functioning catalytic converter should not show any excessive soot or debris buildup.
3. Install the new catalytic converter: Position the new catalytic converter in place and secure it with bolts, tightening to the manufacturer's torque specifications.
4. Reattach exhaust components: Ensure any gaskets are replaced and reassemble the exhaust system securely.

4. Clear Codes and Test

1. Reconnect the battery: Ensure all connections are secure and reattach the battery.
2. Clear the fault codes: Use the OBD-II scanner to reset the check engine light.
3. Test drive the vehicle: Monitor the vehicle for performance and check that the check engine light does not re-illuminate.