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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, smoke machine (if applicable)
• Safety Warnings: Disconnect the battery before working on electrical systems. Allow the engine to cool before opening any components.

2. Replace Oxygen Sensors (if faulty)

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) sensors.
2. Disconnect the battery: Ensure safety by disconnecting the negative terminal.
3. Unplug the sensors: Carefully detach the wiring harness from both oxygen sensors.
4. Remove old sensors: Use an oxygen sensor socket to unscrew and remove the sensors from the exhaust system.
5. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them. Torque to manufacturer specifications (typically 30 lb-ft).
6. Reconnect wiring: Plug the wiring harness back into both sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check for signs of clogging: If the catalytic converter appears damaged or the tests show inefficiency, replacement is required.
2. Raise the vehicle: Use a jack and jack stands to elevate the front of the vehicle for access.
3. Remove the exhaust components: Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe using a socket set. Keep the gaskets for reuse if they are in good condition.
4. Install new catalytic converter: Position the new catalytic converter and secure it with bolts. Ensure proper alignment and torque to manufacturer specifications.
5. Reconnect exhaust system: Reattach any removed exhaust components, ensuring all connections are secure.

4. Clear the Codes

1. Reconnect the battery: Ensure the negative terminal is securely connected.
2. Clear the stored codes: Use the OBD-II scanner to erase the P0420 code from the vehicle's memory.
3. Test drive the vehicle: Drive for a short distance to allow the engine control unit (ECU) to monitor the new components.