how to diagnose P0171 code on my Volkswagen Golf Eighth Generation (2020-present)?

Solution

1. Preparation

• Gather tools and ensure the vehicle is parked on a flat surface with the engine cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect Air Intake System

• Step 1: Visually inspect the intake hoses and connections for any signs of wear or damage.
• Step 2: Use a smoke machine to detect vacuum leaks if necessary.
• Step 3: Tighten or replace any damaged hoses or clamps.

3. Clean or Replace MAF Sensor

• Step 1: Locate the MAF sensor in the air intake duct.
• Step 2: Disconnect the electrical connector and remove the sensor from the duct.
• Step 3: Use MAF cleaner spray to clean the sensor elements; do not touch them with hands or tools.
• Step 4: Reinstall the sensor and reconnect the electrical connector.

4. Check Fuel System Pressure

• Step 1: Connect a fuel pressure gauge to the fuel rail service port.
• Step 2: Turn the ignition to the "ON" position without starting the engine to check the pressure reading.
• Step 3: Compare the reading to manufacturer specifications; replace the fuel pump if it’s low.

5. Inspect Fuel Injectors

• Step 1: Remove the fuel rail assembly to access the injectors.
• Step 2: Visually inspect injectors for leaks or clogs.
• Step 3: Clean the injectors with an appropriate fuel injector cleaning solution or replace them if necessary.

6. Test Oxygen Sensors

• Step 1: Locate the upstream oxygen sensor (before the catalytic converter).
• Step 2: Use a multimeter to measure voltage output while the engine is running; it should fluctuate between 0.1 to 0.9 volts.
• Step 3: Replace the oxygen sensor if it does not provide the correct readings.