What make system too lean 2000 beetle?

Therecan benumerous reasonsfor this. Mainly need to make sure there are no vacuum leaks, look and listen for vacuum hoses cracked or disconnected. Sometimes fuel injectors need to be cleaned. The Mass Air Flow sensor mayneed cleaningor a leak in the hoses connecting it to the engine. I always try just resetting the code and see if it goes away first, may need to be reset a couple of times and then it stops coming back. If it persists and there are no obvious things like I mentioned, then it's time to go to a technician.