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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, backpressure gauge.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to avoid electrical shorts.

2. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and disconnect its electrical connector.
  2. Use a multimeter to check the sensor’s voltage output (should fluctuate between 0.1 to 0.9 volts).
  3. Repeat the process for the downstream (post-catalytic) oxygen sensor.
  4. If either sensor is faulty, replace it.

3. Inspect Catalytic Converter

• Sub-steps:
  1. Visually inspect the catalytic converter for physical damage or signs of clogging.
  2. If any damage is noted, remove the catalytic converter using a socket set.
  3. Check the converter for excessive carbon build-up or internal failure.
  4. Replace the catalytic converter if necessary, ensuring proper fit and sealing.

4. Repair Exhaust Leaks

• Sub-steps:
  1. Inspect the entire exhaust system for any leaks, especially near the manifold and catalytic converter.
  2. Use exhaust sealant for minor leaks or replace damaged sections of the exhaust pipe.
  3. Reconnect any disconnected exhaust components securely.

5. Clear Error Codes

• Sub-steps:
  1. Reconnect the battery.
  2. Use an OBD-II scanner to clear the P0420 code.
  3. Take the vehicle for a test drive to monitor for any reoccurrence of the check engine light.