how to fix P0420 code on Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative terminal of the battery to ensure safety.

2. Replace Oxygen Sensors (if faulty)

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic) and/or downstream (post-catalytic) oxygen sensors:
  • Locate the sensors (usually positioned on the exhaust pipe).
  • Use the O2 sensor socket to unscrew the sensors counterclockwise.
• Install new oxygen sensors:
  • Apply anti-seize compound to the threads of the new sensors if required.
  • Screw in the new sensors and tighten to manufacturer specifications (typically around 30 ft-lbs).

3. Inspect or Replace the Catalytic Converter

• Tools Required: Jack and jack stands, wrench set, exhaust gasket.
• If the catalytic converter is faulty:
  • Raise the vehicle and secure it on jack stands.
  • Unbolt the catalytic converter from the exhaust manifold and the muffler using a wrench.
  • Remove and inspect the old catalytic converter for damage.
  • Install the new catalytic converter:
    • Position it correctly and bolt it in place, ensuring a proper seal with exhaust gaskets.
    • Torque bolts to manufacturer's specifications (usually around 25 ft-lbs).

4. Reset the Check Engine Light

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.