how to fix P0420 code on my Toyota RAV4 XA40 (2013-2018)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal for safety.

2. Inspect and Test Oxygen Sensors

• Remove the upstream (pre-cat) oxygen sensor using a socket wrench.
• Test the sensor using a multimeter; check for proper voltage output (0.1-0.9 volts).
• If the sensor is faulty, replace it with a new one.

3. Inspect Catalytic Converter

• Raise the vehicle securely on jack stands.
• Inspect the catalytic converter visually for physical damage.
• Perform a backpressure test:
  • Insert a pressure gauge into the oxygen sensor port.
  • Start the engine and observe the reading; a reading over 2.5 PSI at idle indicates a clogged converter.
• If clogged, replace the catalytic converter.

4. Repair Exhaust Leaks

• Inspect the exhaust manifold and piping for leaks.
• Tighten any loose bolts or replace gaskets as necessary.

5. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Test drive the vehicle to ensure the check engine light does not return.