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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle safely using jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensor connectors for corrosion or damage; clean or replace if necessary.
• Install new oxygen sensors, torquing to manufacturer specifications (typically around 30 lb-ft).

3. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, penetrating oil, exhaust hanger tool.
• Remove the exhaust hangers to free the exhaust system from the chassis.
• Unbolt the old catalytic converter from the exhaust pipe and manifold, applying penetrating oil to stubborn bolts.
• Install the new catalytic converter, ensuring that all gaskets are replaced and connections are secure.
• Torque all bolts to manufacturer specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the ECM.
• Start the engine and let it idle for a few minutes to ensure proper operation.