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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Allow the exhaust system to cool before beginning work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: Oxygen sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic converter) oxygen sensor:
  1. Locate the upstream oxygen sensor (usually near the exhaust manifold).
  2. Use the oxygen sensor socket to carefully unscrew the sensor.
  3. Install the new oxygen sensor and torque to the manufacturer’s specifications (typically around 30 lb-ft).
• Repeat for the downstream (post-catalytic converter) oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting tool (if needed), torque wrench, gasket scraper.
• If the catalytic converter is found to be damaged or inefficient:
  1. Disconnect the exhaust pipes connected to the catalytic converter.
  2. Remove any bolts or clamps that secure the catalytic converter.
  3. If necessary, cut the exhaust pipes with a cutting tool to remove the old catalytic converter.
  4. Clean the mating surfaces on the exhaust pipes.
  5. Install the new catalytic converter, ensuring proper alignment.
  6. Reattach exhaust pipes and secure with bolts or clamps, torquing to manufacturer specifications.

4. Reset Engine Control Module (ECM)

• After repairs, reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the ECM.