how to fix P0420 code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, safety goggles, gloves.
• Ensure the vehicle is on a level surface and the engine is cool. Disconnect the battery to prevent electrical hazards.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use a socket wrench to carefully unscrew the oxygen sensors from the exhaust system.
  3. Install new oxygen sensors by reversing the removal procedure. Ensure they are tightened to the manufacturer’s specifications (usually around 30-40 ft-lbs).
  4. Reconnect the wiring harness to each sensor.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Verify the condition of the catalytic converter; look for any physical damage or blockages.
  2. If the converter is faulty, remove the exhaust pipes connected to it using a socket wrench.
  3. Unbolt the catalytic converter from its mounting points.
  4. Install the new catalytic converter by reversing the removal steps, ensuring all bolts are torqued to specifications.
  5. Reattach any exhaust hangers and pipes securely.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and let it reach operating temperature.
  4. Take the vehicle for a test drive under various conditions to ensure proper operation.