how to fix P0420 code on Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical issues.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the electrical connectors from both the upstream and downstream oxygen sensors.
• Using the multimeter, test the voltage output of each sensor while the engine is running. The upstream O2 sensor should fluctuate between 0.1 to 0.9 volts.
• If the readings are outside this range or the sensor is unresponsive, replace the faulty oxygen sensor.

3. Inspect the Catalytic Converter

• Tools Required: Socket set, torque wrench
• Locate the catalytic converter and inspect it for physical damage such as dents or rust.
• Check the inlet and outlet sides for any signs of blockage. If the converter is damaged or clogged, replace it.
• If no physical damage is found, proceed with cleaning the catalytic converter using a proper catalytic converter cleaner.

4. Reassemble and Clear Codes

• Reconnect the oxygen sensors and ensure all connections are secure.
• Reconnect the negative battery terminal.
• Start the vehicle and allow it to run for a few minutes.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.