how to fix P0420 code on my Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Backpressure gauge

2. Inspect and Replace Oxygen Sensors

1. Remove the Oxygen Sensors:
   • Locate both the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
   • Use a socket or wrench to carefully unscrew the sensors from their mounting points.
2. Inspect and Test:
   • Use the multimeter to check the resistance and voltage output of both sensors as per manufacturer's specifications.
3. Replace Defective Sensors:
   • If either sensor is faulty, install a new one. Apply anti-seize compound to the threads of the new sensors to ensure easy removal in the future.
   • Torque the sensors to the manufacturer's specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check for Blockages:
   • Using a backpressure gauge, connect it to the exhaust before the catalytic converter and start the engine. A reading above 1.5 psi at idle may indicate a blockage.
2. Remove the Catalytic Converter:
   • Disconnect the exhaust pipes from the catalytic converter using a socket set.
   • Remove any mounting brackets or heat shields if necessary.
3. Install New Catalytic Converter:
   • Position the new catalytic converter and secure it in place with the mounting bolts.
   • Reattach the exhaust pipes, ensuring a proper seal.
   • Torque all connections to the specifications provided in the service manual.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.