how to fix P0420 code on my Genesis G70 IG (2017-2023)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts during work.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor (usually located before the catalytic converter):

   • Tools Required: O2 sensor socket, ratchet, and extension.
   • Safety Warning: Ensure the engine is cool before touching exhaust components.

2. Check the sensor's resistance using a multimeter:

   • If it's out of specification, replace it.

3. Install a new upstream oxygen sensor:

   • Torque the sensor to the manufacturer’s specification (typically around 30-40 lb-ft).

4. Repeat for the downstream oxygen sensor if necessary, following the same steps.

3. Replace Catalytic Converter (if necessary)

1. Remove the catalytic converter:

   • Tools Required: Socket set, penetrating oil, and a cutting tool if bolts are rusted.
   • Safety Warning: Use safety glasses and gloves to protect from exhaust debris.

2. Inspect the old catalytic converter for signs of damage, clogging, or contamination.

3. Install a new catalytic converter:

   • Ensure proper alignment with exhaust flanges.
   • Torque to manufacturer’s specification.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code from the ECM.