Cal. Bus. & Prof. Code § 21304
(a) This chapter does not require an original equipment manufacturer to divulge a trade secret, except as necessary to provide documentation, parts, tools, service access methods, and training courses and materials on fair and reasonable terms.
(c) An original equipment manufacturer is not liable for faulty or otherwise improper repairs provided by independent repair providers or owners, including faulty or otherwise improper repairs that cause any of the following: