my Tesla Outback 5th Generation (2015-2019) has a check engine light and code P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to prevent electrical shorts.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) sensors.
2. Remove the oxygen sensors:
   • Use an oxygen sensor socket to remove the upstream sensor first.
   • Disconnect the electrical connector.
   • Repeat for the downstream sensor.
3. Install new oxygen sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the upstream sensor and torque to the manufacturer's specification (usually around 30 lb-ft).
   • Connect the electrical connector.
   • Repeat for the downstream sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Assess the catalytic converter: If the oxygen sensors are functioning correctly, inspect the catalytic converter for damage or blockage.
2. Remove the catalytic converter:
   • Loosen and remove the bolts or clamps securing the catalytic converter to the exhaust system.
   • Carefully detach the converter from the exhaust pipes.
3. Install a new catalytic converter:
   • Position the new converter in place.
   • Secure it with new gaskets and bolts, torquing to specifications (typically around 40 lb-ft).
4. Reconnect exhaust components: Ensure all exhaust components are properly secured.

4. Reset Engine Control Module (ECM)

1. Reconnect the battery: Ensure the battery is reconnected securely.
2. Clear the codes: Use the OBD-II scanner to reset the check engine light and clear any stored error codes.