what causes my Volkswagen Passat B8 (2015-2022) dashboard warning lights to stay on

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, fuse puller, safety glasses, gloves.
• Ensure the vehicle is parked on a level surface and the engine is turned off.

2. Scan for Error Codes

• Connect the OBD-II scanner to the vehicle’s diagnostic port.
• Turn the ignition to the "ON" position without starting the engine.
• Follow the scanner prompts to read and save the error codes.

3. Inspect Battery and Charging System

• Tools Required: Multimeter.
• Disconnect the battery terminals (negative first).
• Use the multimeter to check the battery voltage (should be around 12.6V for a fully charged battery).
• Start the engine and check the voltage again (should be between 13.7V and 14.7V).
• Replace the battery if voltage is low or the charging system is faulty.

4. Check Fuses

• Locate the fuse box (refer to the owner's manual for location).
• Inspect relevant fuses for the dashboard and warning light systems.
• Replace any blown fuses with the correct amperage rating.

5. Inspect Sensors and Modules

• Visually inspect wiring and connectors for any damage or corrosion.
• Test individual sensors (like brake pressure or oil pressure) using the multimeter for proper operation.
• Replace any faulty sensors or modules.

6. Clear Error Codes

• After addressing all issues, use the OBD-II scanner to clear the error codes.
• Restart the engine and monitor if warning lights reappear.