how to fix P0171 lean code in Volkswagen Golf MK7.5 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Tools Required: OBD-II scanner, multimeter, torque wrench, socket set, vacuum gauge.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses and connections for cracks or disconnections.
  2. Use a vacuum gauge to test the intake manifold for leaks.
  3. If any leaks are found, replace the affected hoses or gaskets.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the intake tract.
  2. Disconnect the electrical connector and remove the sensor using a Torx bit.
  3. Clean the MAF sensor with MAF cleaner or replace it if damaged.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel System Components

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail to check fuel pressure.
  2. If pressure is low, inspect the fuel pump and filter. Replace the fuel filter if necessary.
  3. If the fuel pump is faulty, replace it according to the manufacturer’s specifications.

5. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor (pre-cat) and disconnect the electrical connector.
  2. Use a multimeter to check the voltage output of the sensor; it should oscillate between 0.1V and 0.9V.
  3. If the sensor is not functioning properly, replace it.

6. Check Engine Coolant Temperature Sensor

• Sub-steps:
  1. Locate the engine coolant temperature sensor and disconnect the connector.
  2. Using a multimeter, measure the resistance of the sensor at various temperatures to ensure it is within the specified range.
  3. Replace the sensor if it is out of specification.