She can garnish up to 50 percent of your pay for the amount you are behind. She can also Leviy your bank account, intercept tax refunds, have your driver's or business license suspended and prevent you from renewing your passport or professional license.
If you are up-to-date and have a good payment record she can't garnishee but if you have a history of not paying, California allows the garnishment to continue until the child reaches the age of 18 in cases where the judge believes that's the only way it will be paid.