my Toyota RAV4 Fifth Generation (2019-present) check engine light is always on what should I do

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, basic hand tools
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Retrieve and Analyze Codes

• Connect the OBD-II scanner to the diagnostic port.
• Turn the ignition to the "ON" position (do not start the engine).
• Retrieve and note the error codes displayed on the scanner.
• Refer to a repair manual or database to interpret the codes.

3. Address Specific Issues

• Based on the retrieved codes, perform targeted repairs:
  • If P0420 (Catalytic Converter Efficiency):
    • Inspect and, if necessary, replace the catalytic converter.
  • If P0171 (System Too Lean):
    • Check for vacuum leaks, inspect MAF sensor, and replace as needed.
  • If P0300 (Random Misfire):
    • Inspect spark plugs, ignition coils, and fuel injectors; replace as necessary.

4. Recheck Gas Cap

• Ensure the gas cap is tightened properly; replace if damaged.

5. Clear Codes and Test

• Clear the error codes using the OBD-II scanner.
• Reconnect the battery terminal.
• Start the vehicle and monitor the check engine light for re-illumination.