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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, pry bar, safety glasses, gloves.
• Park the vehicle on a flat surface and ensure the engine is cool before starting work.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:
   • The upstream sensor is located before the catalytic converter, and the downstream sensor is after it.
2. Remove the Oxygen Sensors:
   • Use a socket wrench to carefully unscrew both sensors.
   • Disconnect the wiring harness by pressing the release tab.
3. Test the Sensors:
   • Use a multimeter to check the voltage output of the sensors. The upstream sensor should fluctuate between 0.1V and 0.9V while the engine is running. If it's outside this range, replace it.
4. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Screw in the new sensors hand-tight, then use a torque wrench to tighten to manufacturer specifications (usually around 30 ft-lbs).
   • Reconnect the wiring harness.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Inspect the Catalytic Converter:
   • Look for any signs of physical damage, such as dents or rust.
2. Remove the Catalytic Converter:
   • Loosen the bolts connecting the catalytic converter to the exhaust system using a socket set.
   • Carefully detach the converter from the exhaust pipes.
3. Install New Catalytic Converter:
   • Position the new catalytic converter and align it with the exhaust pipes.
   • Secure it using the original or new bolts, tightening to manufacturer specifications.
4. Reconnect Exhaust System:
   • Ensure all connections are secure and leak-free.