how to troubleshoot a check engine light on my Toyota Highlander Fourth Generation (2020-present)?

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, multimeter, torque wrench.
• Disconnect the negative battery terminal to reset the ECU (Engine Control Unit) and ensure safety during inspection.

2. Addressing Fault Codes

• Use the OBD-II scanner to pull the stored trouble codes.
• Cross-reference the codes with a repair manual or online database to pinpoint the issue (e.g., P0420 for catalytic converter efficiency).

3. Repairing Detected Issues

• For Sensor Issues (e.g., O2 sensor):
  • Remove the faulty sensor using a socket.
  • Replace with a new sensor, ensuring the correct torque specifications (typically 20-30 ft-lbs).
• For Vacuum Leaks:
  • Locate and replace damaged vacuum hoses or gaskets.
  • Ensure all connections are secure and tested for leaks after installation.
• For Ignition or Fuel System Issues:
  • Inspect spark plugs and replace if worn or fouled.
  • Check fuel injectors for proper operation and clean or replace as necessary.

4. Resetting the Check Engine Light

• After completing repairs, reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any trouble codes stored in the ECU.