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.
• Raise the vehicle and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on Bank 1.
  2. Use an O2 sensor socket to carefully remove the sensors.
  3. Inspect the sensors for damage or contamination; replace if necessary.
  4. Install new oxygen sensors, tightening them to manufacturer specifications (usually 30-40 lb-ft).

3. Check and Replace Catalytic Converter (if defective)

• Sub-steps:
  1. Inspect the catalytic converter for signs of physical damage or clogging.
  2. If replacement is needed, unbolt the catalytic converter from the exhaust system using a socket set.
  3. Clean the exhaust flanges and remove any old gaskets.
  4. Install the new catalytic converter with new gaskets, tightening bolts to the specified torque (typically 25-35 lb-ft).

4. Reset the ECU

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0421 code from the ECU.

5. Final Inspection

• Sub-steps:
  1. Start the engine and let it reach operating temperature.
  2. Inspect for leaks in the exhaust system.
  3. Monitor engine performance and check for reoccurrence of the P0421 code.