Common symptoms:
- Loss of power, especially at lower RPMs
- Rough idle
- Check engine light (codes related to VANOS)
- Rattling noise from the front of the engine
- Perform OBD-II scan for VANOS-related codes
- Check oil pressure at the VANOS unit
- Inspect VANOS solenoids and seals
- Perform VANOS adjustment test using specialized BMW software
- Replace VANOS seals (common and relatively inexpensive fix)
- Clean or replace VANOS solenoids
- Rebuild VANOS unit
- In severe cases, replace entire VANOS system
