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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure vehicle is parked on a flat surface and is securely raised with jack stands.
• Disconnect the battery to avoid any electrical issues.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:

   • Use an oxygen sensor socket to carefully unscrew the sensor from the exhaust manifold.
   • Disconnect the electrical connector.

2. Install the new upstream oxygen sensor:

   • Apply anti-seize compound to the threads of the new sensor.
   • Screw the sensor in place and connect the electrical connector.
   • Torque to manufacturer specifications (typically around 30 ft-lbs).

3. Repeat for the downstream oxygen sensor:

   • Access and remove the downstream oxygen sensor similarly.
   • Install the new sensor and torque to specifications.

3. Inspect Catalytic Converter

1. Visual inspection:
   • Check for any dents, holes, or signs of overheating.
2. Check for restrictions:
   • If accessible, use a backpressure gauge to measure exhaust backpressure at the O2 sensor port.
   • If backpressure exceeds manufacturer specifications, replacement may be necessary.

4. Replace Catalytic Converter (if necessary)

1. Remove old catalytic converter:
   • Disconnect any exhaust hangers and support brackets.
   • Unbolt the catalytic converter from the exhaust pipes using a socket set.
2. Install new catalytic converter:
   • Position the new converter and secure it with bolts.
   • Reattach any hangers and brackets.
   • Torque bolts to manufacturer specifications.

5. Clear Codes and Test

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the error codes.
3. Test drive the vehicle: Monitor for any reoccurrence of the P0420 code.