how to fix P0421 code on Tesla Model S Original (2012-2020)

Learn how to diagnose and fix P0421 exhaust system issue in Tesla Model S (2012-2020). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and ensure it is in "Park" mode.
• Disconnect the battery (negative terminal) for safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set.
• Remove the upstream (pre-catalytic converter) oxygen sensor:
  1. Locate the oxygen sensor connector and unplug it.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust pipe.
• Install the new oxygen sensor:
  1. Apply anti-seize compound on the threads of the new sensor.
  2. Screw the new O2 sensor into the exhaust pipe and torque to manufacturer's specifications.
  3. Reconnect the sensor's electrical connector.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench.
• Remove the catalytic converter:
  1. Disconnect any exhaust hangers or supports securing the catalytic converter.
  2. Unbolt the catalytic converter from the exhaust system, taking note of any gaskets or seals.
• Install the new catalytic converter:
  1. Position the new converter in place and secure it using new gaskets and bolts.
  2. Torque the bolts to the manufacturer's specifications.

4. Clear Error Codes

• Reconnect the battery and start the vehicle.
• Use the OBD-II scanner to clear the P0421 code from the vehicle's computer.

5. Test Drive

• Take the vehicle for a test drive under various conditions to ensure proper operation and that the check engine light does not reappear.