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

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool completely to avoid burns.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Identify the pre-catalytic converter (upstream) and post-catalytic converter (downstream) oxygen sensors.
• Disconnect the electrical connectors from both oxygen sensors.
• Remove the old sensors using the O2 sensor socket.
• Apply anti-seize compound to the threads of the new sensors (if applicable).
• Install the new sensors and torque them to manufacturer specifications (typically around 30 ft-lbs).
• Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust hanger removal tool
• Raise the vehicle securely on jack stands.
• Inspect the catalytic converter for physical damage, rust, or clogging.
• If damaged, remove the bolts or clamps securing the catalytic converter to the exhaust system.
• Disconnect the exhaust hangers using an exhaust hanger removal tool.
• Remove the old catalytic converter.
• Install the new catalytic converter and secure it using bolts or clamps, torquing to specifications.
• Reattach the exhaust hangers.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes.
• Take the vehicle for a test drive to monitor for any reoccurrence of the check engine light.