how to fix P0420 catalyst efficiency code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to prevent electrical shorts.
• Allow the engine to cool before proceeding to avoid burns.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:

   • Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.

2. Remove the Oxygen Sensors:

   • Use an oxygen sensor socket to remove both sensors carefully.
   • Disconnect the wiring harness from each sensor.

3. Install New Oxygen Sensors:

   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors by hand to avoid cross-threading, and tighten them to manufacturer specifications (typically 30-40 ft-lbs).

3. Inspect and Replace the Catalytic Converter

1. Remove the Exhaust System Components:

   • Depending on the design, you may need to remove the heat shield or any bolts connecting the catalytic converter to the exhaust system.
   • Use a socket set and appropriate extensions to access hard-to-reach bolts.

2. Remove the Old Catalytic Converter:

   • Detach the catalytic converter from the exhaust pipes. If it's rusted, you may need to use a penetrating fluid.
   • Carefully lower the converter to avoid damaging surrounding components.

3. Install the New Catalytic Converter:

   • Position the new catalytic converter in place and attach it securely to the exhaust pipes.
   • Make sure to tighten all bolts to the manufacturer's torque specifications.

4. Final Checks

1. Reconnect Battery and Clear Codes:

   • Reconnect the negative battery terminal.
   • Use the OBD-II scanner to clear the P0420 code and any other related codes.

2. Test Drive the Vehicle:

   • Take the vehicle for a test drive to ensure the check engine light does not reappear and the vehicle runs smoothly.