how to fix the P0420 code on my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, infrared thermometer, socket set, jack and jack stands.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Raise the vehicle safely using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:
   • Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the Upstream Oxygen Sensor:
   • Use a socket wrench to remove the upstream oxygen sensor from the exhaust manifold.
3. Install New Oxygen Sensor:
   • Install the new upstream oxygen sensor. Torque to manufacturer's specifications (usually around 30 ft-lbs).
4. Remove the Downstream Oxygen Sensor:
   • Repeat the process for the downstream oxygen sensor.
5. Install New Downstream Oxygen Sensor:
   • Install the new downstream oxygen sensor and torque it to specification.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Inspect the Catalytic Converter:
   • Check for physical damage, rattling noises, or excessive heat using an infrared thermometer.
2. Remove the Catalytic Converter:
   • Disconnect the exhaust pipe from the catalytic converter using the appropriate socket.
   • Unbolt the catalytic converter from the exhaust system and remove it.
3. Install New Catalytic Converter:
   • Place the new catalytic converter in position and secure it with bolts. Torque to specification.
   • Reconnect the exhaust pipe and ensure all connections are tight.

4. Reset the Engine Control Module (ECM)

1. Reconnect Battery:
   • Reconnect the negative battery terminal.
2. Clear the Codes:
   • Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Test Drive:
   • Drive the vehicle for at least 20 minutes to allow the ECM to recalibrate and check for any new codes.