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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust pipe cutter (if necessary).
• Clear the P0420 code using the OBD-II scanner.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:
   • Identify the upstream sensor (pre-catalytic converter) and the downstream sensor (post-catalytic converter).
2. Disconnect Electrical Connectors:
   • Use a flathead screwdriver to gently pry off the connectors from the sensors.
3. Remove the Sensors:
   • Use an oxygen sensor socket to unscrew the sensors from the exhaust system.
4. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors and install them.
   • Torque to manufacturer specifications (typically around 30-40 lb-ft).
5. Reconnect the Connectors:
   • Ensure the electrical connectors are securely attached to the new sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Inspect the Catalytic Converter:
   • Look for signs of physical damage, such as dents or rust.
   • Shake the converter gently to check for loose internals.
2. Remove the Catalytic Converter:
   • Cut the exhaust pipes with an exhaust pipe cutter if necessary.
   • Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
3. Install New Catalytic Converter:
   • Position the new catalytic converter in place.
   • Bolt it to the exhaust manifold and the exhaust pipe, torquing to manufacturer specifications (usually around 25-30 lb-ft).
4. Reconnect Any Removed Components:
   • Ensure all exhaust connections are tight and secure.

4. Final Steps

• Reconnect the battery (if disconnected).
• Start the engine and let it idle for a few minutes.
• Check for any exhaust leaks around the repaired areas.