why does my Toyota Highlander XU70 (2020-Present) have a check engine light with P0174 code?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before beginning any work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Hose clamps, vacuum gauge, and a flashlight.
• Visually inspect all vacuum lines and connections from the intake manifold to the throttle body.
• Use a vacuum gauge to test for leaks; if found, replace damaged hoses or tighten loose connections.

3. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner.
• Remove the MAF sensor from the air intake duct.
• Spray MAF cleaner onto the sensor element without touching it; allow it to dry completely before reinstalling.
• Reinstall the MAF sensor securely.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge and adapter.
• Connect the fuel pressure gauge to the fuel rail's test port.
• Start the engine and check the pressure; it should meet manufacturer specifications (typically between 50-60 psi).
• If pressure is low, inspect the fuel pump and filter for issues.

5. Replace Fuel Filter (if necessary)

• Tools Required: Wrenches, new fuel filter, and rags.
• Locate the fuel filter (usually along the fuel line).
• Disconnect the fuel lines carefully, allowing any excess fuel to drain into a rag.
• Replace the old filter with a new one, ensuring proper orientation.
• Reconnect the fuel lines and check for leaks.

6. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0174 code and perform a test drive to verify the repair.