my Volkswagen Passat B8 (2015-2022) has a check engine light and bad fuel economy

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Replace Engine Air Filter

• Remove the air filter housing cover using a socket set.
• Take out the old air filter and replace it with a new one.
• Reassemble the air filter housing and secure it properly.

3. Clean or Replace MAF Sensor

• Disconnect the MAF sensor connector.
• Remove the MAF sensor from the intake duct.
• Clean the sensor with MAF cleaner or, if heavily contaminated, replace it with a new unit.
• Reinstall the MAF sensor and reconnect the electrical connector.

4. Inspect and Replace Spark Plugs

• Remove the ignition coil cover using a socket set.
• Disconnect each ignition coil and remove them to access the spark plugs.
• Use a spark plug socket to remove old spark plugs and inspect them for wear.
• Install new spark plugs, ensuring to use the manufacturer-recommended torque value (typically 22 lb-ft).
• Reinstall the ignition coils and cover.

5. Check for Vacuum Leaks

• Inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Replace any damaged hoses and secure all connections.
• Use a smoke machine to detect leaks if necessary.

6. Final Checks

• Reconnect the battery.
• Clear any error codes using the OBD-II scanner and perform a test drive to check for the reappearance of the check engine light.