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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery to prevent electrical shorts.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Exhaust pipe cutter (if necessary)
• Safety goggles and gloves

2. Inspect and Replace Oxygen Sensors

1. Remove the oxygen sensor wiring harness connectors by pressing the clips and pulling them apart.
2. Use a socket wrench to unscrew the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors from their respective locations.
3. Install the new oxygen sensors by threading them into the exhaust manifold and the catalytic converter, respectively.
4. Tighten them to the manufacturer’s specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

1. If the catalytic converter is damaged or inefficient, remove it:
   • Use a socket set to loosen and remove the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
   • If necessary, use an exhaust pipe cutter to remove any sections that are too rusted or damaged.
2. Install the new catalytic converter:
   • Position it correctly between the exhaust manifold and the exhaust pipe.
   • Secure it with the bolts and tighten them to the manufacturer’s specifications.
3. Reconnect any heat shields or brackets that were removed.

4. Reconnect Battery and Clear Codes

1. Reconnect the battery terminals, ensuring a tight connection.
2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
3. Start the engine and allow it to reach operating temperature.