how to fix the P0420 code on my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Use an O2 sensor socket to unscrew the sensor from the exhaust manifold.
   • Disconnect the electrical connector.
2. Install a new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Screw the new sensor into place and connect the electrical connector.
3. Repeat for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter (if needed)

1. Remove the exhaust components:
   • Use a socket set to remove the bolts securing the exhaust pipes to the catalytic converter.
   • Support the exhaust system to prevent damage while removing the converter.
2. Inspect the catalytic converter:
   • Check for physical damage, signs of clogging, or contamination.
3. Install a new catalytic converter:
   • Position the new catalytic converter and secure it with the original or new bolts.
   • Ensure all gaskets are properly seated to prevent leaks.

4. Reset the Engine Control Module (ECM)

1. Reconnect the battery:
   • Ensure all connections are tight and secure.
2. Clear the P0420 code:
   • Use an OBD-II scanner to clear the trouble codes from the ECM.