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

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands, exhaust sealant, and safety glasses.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the battery to avoid any electrical shorts.

2. Oxygen Sensor Replacement (if faulty)

• Tools Required: O2 sensor socket or wrench, torque wrench
• Remove the connector from the faulty oxygen sensor (usually the post-cat sensor).
• Use the O2 sensor socket to remove the old sensor by turning it counterclockwise.
• Apply anti-seize compound to the threads of the new sensor.
• Install the new sensor by threading it into the exhaust pipe and tightening it to the manufacturer's specified torque (usually around 30-40 ft-lbs).
• Reconnect the sensor's electrical connector.

3. Catalytic Converter Replacement (if necessary)

• Tools Required: Socket set, torque wrench, exhaust sealant
• Raise the vehicle using a jack and secure it with jack stands.
• Remove the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe using a socket set.
• Inspect the gasket and replace it if damaged.
• Position the new catalytic converter and secure it with the bolts, tightening to the manufacturer's specified torque (usually around 30-35 ft-lbs).
• Apply exhaust sealant to joints to prevent leaks.
• Lower the vehicle back to the ground.