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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on the vehicle.
• Raise the vehicle using a jack and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the sensors:

   • Identify the upstream and downstream oxygen sensors in the exhaust system.

2. Remove the sensors:

   • Use an oxygen sensor socket to carefully remove the upstream sensor.
   • Repeat for the downstream sensor if necessary.

3. Install new sensors:

   • Apply anti-seize compound to the threads of the new oxygen sensors.
   • Install the new upstream sensor and tighten to manufacturer specifications (typically around 30 lb-ft).
   • Install the downstream sensor similarly.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check catalytic converter:

   • Inspect for physical damage or excessive heat discoloration.
   • Use a vacuum gauge to check for back pressure in the exhaust system.

2. Remove exhaust components:

   • Detach any exhaust pipes or brackets holding the catalytic converter in place using a socket set.
   • Remove the catalytic converter.

3. Install new catalytic converter:

   • Place the new catalytic converter in the same position.
   • Reattach all exhaust components, ensuring all bolts are torqued to specifications.

4. Clear Codes and Test

1. Reconnect battery:

   • Reconnect the battery terminals securely.

2. Clear the fault codes:

   • Use the OBD-II scanner to clear any existing fault codes.

3. Test drive the vehicle:

   • Drive the vehicle for a short distance to allow the system to recalibrate and monitor for any returning codes.