how to fix P0421 code in Genesis G70 IG (2017-2023)?

Learn how to diagnose and fix P0421 exhaust system issue in Genesis G70 (2017-2023). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool completely before beginning work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-cat) oxygen sensor by:
  1. Disconnect the electrical connector.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust pipe.
  3. Install the new oxygen sensor and torque it to the manufacturer’s specifications (typically around 30 lb-ft).
  4. Reconnect the electrical connector.
• Repeat the process for the downstream (post-cat) oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust gasket, and sealant.
• Raise the vehicle securely on jack stands.
• Remove any heat shields covering the catalytic converter.
• Disconnect the exhaust pipes from the catalytic converter using the socket set.
• Remove any mounting bolts securing the catalytic converter and take it out.
• Install the new catalytic converter, ensuring proper alignment, and secure with mounting bolts to the specified torque.
• Reconnect the exhaust pipes and heat shields.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use the OBD-II scanner to clear any trouble codes from the engine control unit (ECU).
• Start the engine and allow it to reach operating temperature.
• Test drive the vehicle to ensure proper operation and monitor for the check engine light.