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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is securely lifted and supported on jack stands.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Sub-steps:
  1. Remove the upstream (pre-catalytic) O2 sensor using a socket.
  2. Using a multimeter, test the voltage output; it should fluctuate between 0.1V to 0.9V.
  3. Reinstall the upstream O2 sensor and repeat for the downstream (post-catalytic) O2 sensor.
  4. If either sensor is faulty, replace it.

3. Inspect Catalytic Converter

• Tools Required: Socket set, pry bar
• Sub-steps:
  1. Visually inspect the catalytic converter for any physical damage or signs of excessive exhaust backpressure.
  2. If the converter is clogged or damaged, remove it using the socket set.
  3. Compare the condition of the old catalytic converter with the new one before installation.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench
• Sub-steps:
  1. Install the new catalytic converter in the exhaust system.
  2. Use a torque wrench to secure all bolts to the manufacturer’s specifications (usually around 40-50 lb-ft).
  3. Reconnect all exhaust hangers.

5. Reinstall Oxygen Sensors

• Tools Required: Socket set
• Sub-steps:
  1. Reinstall the downstream O2 sensor into the new catalytic converter and torque to specifications.
  2. Reconnect the negative battery terminal.