how to fix P0420 code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, safety glasses, gloves, jack and jack stands.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle securely on jack stands.

2. Inspect and Replace Oxygen Sensors

• 2.1. Remove Upstream Oxygen Sensor:

  • Locate the upstream oxygen sensor (usually near the exhaust manifold).
  • Use a socket wrench to remove the sensor.
  • Inspect the sensor for any signs of damage or contamination.

• 2.2. Install New Upstream Oxygen Sensor:

  • Apply anti-seize compound to the threads of the new sensor.
  • Install the new sensor, torque to manufacturer specifications (typically around 30 lb-ft).

• 2.3. Remove Downstream Oxygen Sensor:

  • Locate the downstream oxygen sensor (after the catalytic converter).
  • Repeat the removal and inspection process as with the upstream sensor.

• 2.4. Install New Downstream Oxygen Sensor:

  • Apply anti-seize compound to the new sensor's threads.
  • Install and torque to specifications.

3. Inspect and Replace Catalytic Converter (if needed)

• 3.1. Remove Catalytic Converter:

  • Unbolt the catalytic converter from the exhaust system, checking for any rust or damage to the mounting points.
  • Lower the converter and inspect for internal damage (e.g., rattling, discoloration).

• 3.2. Install New Catalytic Converter:

  • Position the new catalytic converter in place.
  • Secure it with bolts, ensuring all connections are tight and torqued to specifications (typically around 30 lb-ft).

4. Reset the Check Engine Light

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the ECU.