If you must use a finger to open and lock the blade, you're good. If there is a spring that propels the blade from a closed to open position, you coul dbe in trouble.
Here is the section:
653k. Every person who possesses in the passenger's or driver's
area of any motor vehicle in any public place or place open to the
public, carries upon his or her person, and every person who sells,
offers for sale, exposes for sale, loans, transfers, or gives to any
other person a switchblade knife having a blade two or more inches in
length is guilty of a misdemeanor.
For the purposes of this section, "switchblade knife" means a
knife having the appearance of a pocketknife and includes a
spring-blade knife, snap-blade knife, gravity knife or any other
similar type knife, the blade or blades of which are two or more
inches in length and which can be released automatically by a flick
of a button, pressure on the handle, flip of the wrist or other
mechanical device, or is released by the weight of the blade or by
any type of mechanism whatsoever. "Switchblade knife" does not
include a knife that opens with one hand utilizing thumb pressure
applied solely to the blade of the knife or a thumb stud attached to
the blade, provided that the knife has a detent or other mechanism
that provides resistance that must be overcome in opening the blade,
or that biases the blade back toward its closed position.
For purposes of this section, "passenger's or driver's area" means
that part of a motor vehicle which is designed to carry the driver
and passengers, including any interior compartment or space therein.
If the spring propels it open, you could be arrested and charged with a misdemeanor. If you carry it in a locked position and concealed, you could be charged with a felony per PC 12021.