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

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the negative battery terminal to ensure safety.
• Allow the exhaust system to cool before starting work.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use a socket wrench to remove the upstream oxygen sensor (usually near the exhaust manifold).
3. Inspect the sensor’s wiring and connector for damage; replace if necessary.
4. Install the new upstream oxygen sensor and tighten it to the manufacturer's specification (typically 30 Nm).
5. Repeat the process for the downstream oxygen sensor.

3. Inspect and Replace the Catalytic Converter

1. If the oxygen sensors are functioning properly, proceed to inspect the catalytic converter.
2. Remove any heat shields or clamps securing the catalytic converter using a socket set.
3. Use a torch to heat stubborn bolts if necessary, and remove the catalytic converter.
4. Inspect the old catalytic converter for signs of blockage or damage.
5. Install the new catalytic converter, ensuring all gaskets are in place, and tighten to manufacturer specifications (typically 40 Nm for exhaust bolts).
6. Reinstall any heat shields.

4. Reset the Engine Control Module (ECM)

1. Reconnect the negative battery terminal.
2. Use an OBD-II scanner to clear the P0420 code from the ECM.
3. Start the engine and let it idle for a few minutes.