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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to reset the system and prevent accidental shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Inspect both upstream and downstream oxygen sensors for signs of wear or damage.
• If faulty, remove the old sensors using an O2 sensor socket.
• Install new oxygen sensors, ensuring they are torqued to manufacturer specifications (typically around 30 lb-ft).
• Reconnect the battery.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack stands, wrench set, exhaust sealant
• Raise the vehicle using jack stands and remove any heat shields covering the catalytic converter.
• Disconnect the exhaust pipes from the catalytic converter using the socket set.
• Remove the catalytic converter and inspect for signs of damage or clogging.
• Install a new catalytic converter, ensuring proper alignment and securing with bolts to manufacturer specifications.
• Use exhaust sealant on joints to prevent leaks.

4. Check for Exhaust Leaks

• Start the vehicle and listen for unusual noises that may indicate exhaust leaks.
• Use a smoke machine or soapy water to check for leaks around joints and connections.