how to fix P0420 code on a Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Locate the upstream and downstream oxygen sensors; they should be near the exhaust manifold and after the catalytic converter, respectively.
• Use the O2 sensor socket to carefully unscrew the upstream sensor. Inspect the sensor for contamination or damage.
• Install the new upstream oxygen sensor and torque to manufacturer specifications (usually around 30-40 ft-lbs).
• Repeat the process for the downstream oxygen sensor if it shows signs of failure or is more than 60,000 miles old.

3. Check and Replace the Catalytic Converter

• Tools Required: Socket set, wrench set, exhaust gasket
• Inspect the catalytic converter for any physical damage or clogging. If it is damaged or heavily clogged, it will need to be replaced.
• Remove the bolts securing the catalytic converter to the exhaust system using a socket set.
• If necessary, cut the exhaust pipe to remove the old catalytic converter.
• Install the new catalytic converter, ensuring proper orientation and secure it with the bolts. Use a new exhaust gasket to prevent leaks.
• Torque the bolts to manufacturer specifications.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Test drive the vehicle for at least 20 minutes to ensure the check engine light does not reappear.