how to fix P0420 code on Ford Mustang S650 (2024-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety while working on electrical components.
• Raise the vehicle and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors (if needed)

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an oxygen sensor socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors, ensuring they are properly torqued (typically around 30 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if needed)

• Sub-steps:
  1. Remove the exhaust pipes connected to the catalytic converter using a socket set.
  2. Unbolt the catalytic converter from the exhaust manifold and remove it from the vehicle.
  3. Install the new catalytic converter, ensuring it is aligned correctly and secured with bolts (torque to manufacturer specifications).
  4. Reconnect the exhaust pipes and ensure all connections are sealed.

4. Reset the Engine Control Module (ECM)

• Sub-steps:
  1. Reconnect the battery terminals.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Start the engine and allow it to reach operating temperature.