what does it mean if my Toyota Highlander Third Generation (2014-2019) has a P0420 code

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to prevent electrical issues during repairs.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Exhaust backpressure gauge

2. Inspect and Replace O2 Sensors

• Sub-steps:
  1. Locate the upstream (pre-cat) and downstream (post-cat) O2 sensors in the exhaust system.
  2. Use a socket to remove the faulty O2 sensor(s).
  3. Install the new O2 sensor(s) and torque to specifications (typically around 30 Nm).

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  1. Remove any heat shields or components blocking access to the catalytic converter.
  2. Unbolt the catalytic converter from the exhaust pipes using a socket wrench.
  3. Inspect the old catalytic converter for damage or clogging.
  4. Install the new catalytic converter and torque bolts to specifications (typically around 40 Nm).
  5. Reattach any heat shields or components removed earlier.

4. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the ECM after completing the repairs.