why does my Volkswagen Passat B8 (2015-2022) have a check engine light and low power

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, multimeter, vacuum gauge, fuel pressure gauge.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Clear Error Codes

• Use the OBD-II scanner to clear all existing error codes after making necessary repairs to prevent confusion during testing.

3. Inspect and Replace Air Filter

• Remove the air filter housing cover using a socket set.
• Take out the old air filter and inspect for dirt and debris.
• Replace with a new manufacturer-approved air filter.
• Reassemble the air filter housing securely.

4. Check for Vacuum Leaks

• Inspect all vacuum lines visually for cracks or damage.
• Use a smoke machine or carburetor cleaner to detect leaks while the engine is running.
• Replace any damaged hoses or components.

5. Test Fuel Pressure

• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine and check the pressure reading.
• Refer to the manufacturer specifications for normal fuel pressure values. Replace the fuel pump if the pressure is low.

6. Clean Throttle Body

• Disconnect the battery to prevent electrical issues.
• Remove the throttle body using a socket set.
• Clean the throttle body with an appropriate cleaner and a soft cloth.
• Reinstall and reconnect all connections securely.

7. Inspect Exhaust System

• Visually check for any visible damage to the exhaust pipes and catalytic converter.
• If necessary, use a pressure gauge to test for back pressure in the system.
• Replace any damaged components as needed.