why does my Toyota Highlander Fourth Generation (2020-present) check engine light come on and off

Solution

1. Preparation

• Gather tools and parts necessary for repairs.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to ensure safety.

2. Address Diagnostic Codes

• Connect the OBD-II scanner and note any error codes.
• Research codes related to common issues (e.g., P0420 for catalytic converter inefficiency).
• Clear codes and observe if the check engine light returns.

3. Gas Cap Inspection

• Remove the gas cap and inspect for cracks or damage.
• Clean the cap and the filler neck with a lint-free cloth.
• Reinstall the gas cap securely and confirm it clicks into place.

4. Engine Fluid Check

• Check engine oil level using the dipstick; add oil if necessary.
• Inspect coolant reservoir for proper fluid level and add coolant if low.

5. Electrical System Check

• Use a multimeter to check battery voltage; it should be between 12.4V and 12.7V.
• Tighten any loose connections and clean corrosion from terminals.

6. Fuel Pressure Test

• Connect a fuel pressure gauge to the fuel rail.
• Start the engine and observe the pressure reading; it should match manufacturer specifications.
• If pressure is low, inspect the fuel pump and filter for issues.