California Code, Civil Code - CIV § 1793.26

(1) Requiring, as a condition of the reacquisition of the motor vehicle, that a buyer or lessee who is a resident of this state agree not to disclose the problems with the vehicle experienced by the buyer or lessee or the nonfinancial terms of the reacquisition.

(2) Including, in any release or other agreement, whether prepared by the manufacturer, importer, distributor, dealer, or lienholder, for signature by the buyer or lessee, a confidentiality clause, gag clause, or similar clause prohibiting the buyer or lessee from disclosing information to anyone about the problems with the vehicle, or the nonfinancial terms of the reacquisition of the vehicle by the manufacturer, importer, distributor, dealer, or lienholder.