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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety during repairs.

2. Inspect and Replace Components

2.1 Inspect Oxygen Sensors

• Remove the connectors from the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Use a multimeter to check sensor voltage and resistance. Replace faulty sensors as necessary.

2.2 Check for Exhaust Leaks

• Visually inspect the exhaust system for cracks or holes.
• If leaks are found, repair or replace damaged exhaust components.

2.3 Replace Catalytic Converter (if necessary)

• Remove the exhaust pipe bolts using a socket set.
• Unbolt the catalytic converter from the exhaust manifold and remove it.
• Install the new catalytic converter by reversing the removal steps. Ensure all bolts are torqued to the manufacturer’s specifications (typically around 30-40 ft-lbs).

3. Reconnect Electrical Connectors

• Reconnect the oxygen sensor connectors to their respective sensors.
• Ensure all connections are secure to prevent any electrical issues.

4. Reset the Engine Control Module (ECM)

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the ECM.