how to fix P0171 code in my Volkswagen Golf MK5 (2004-2008)

Solution

1. Preparation

• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Gather necessary tools and parts.

2. Inspect and Repair Air Intake System

• Tools Required: Vacuum gauge, hose clamps, screwdriver set
• Inspect all vacuum hoses for cracks or disconnections; replace any damaged hoses.
• Check the intake manifold gasket for leaks; replace if necessary.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, torque wrench
• Remove the MAF sensor from the intake duct using a screwdriver.
• Clean the sensor with MAF sensor cleaner; allow it to dry completely.
• Reinstall the MAF sensor and tighten to the manufacturer’s specifications.

4. Check Fuel System

• Tools Required: Fuel pressure gauge, wrench set
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the ON position (without starting the engine) to check fuel pressure.
• If pressure is below specifications, inspect the fuel pump and replace it if faulty.
• Check the fuel filter and replace if clogged.

5. Inspect Fuel Injectors

• Tools Required: Injector cleaning kit (if needed)
• Remove fuel injectors from the rail and inspect for clogs or leaks.
• Clean injectors using an injector cleaning kit, or replace them if defective.