Vehicles that are 1996 and newer do not have a Thermostatic Air Cleaner (TAC) system because these vehicles are equipped with OBDII (On-Board Diagnostics – Second Generation) computer systems with more sophisticated fuel injection and emissions control systems, so there’s no need for a TAC system. Vehicles that are originally manufactured without a TAC system can have any type of aftermarket open-type air filter/intake system installed because this type of system is not an item of inspection.
NOTE: If the air intake system reads "For Racing Purposes Only" or "For Off Road Use Only," then it is not intended for use on public roadways and is not street legal. If the air intake system is CARB approved and 50-state legal, then it is street legal in all 50 states.
Vehicles that are 1995 and older and originally manufactured with a TAC system are required to have a closed-type air cleaner/filter system to reduce carbon monoxide and hydrocarbon emissions during cold engine operation. All the components must be in place in order to pass the visual emissions component inspection, which is part of the annual safety inspection.
The TAC system consists of the enclosed air cleaner/filter assembly and a heat shroud at the exhaust manifold and then there is also a heat duct hose that connects from the heat shroud to the air cleaner assembly. Also, some of the TAC systems had a fresh air duct hose that attached from the front or side of the air cleaner assembly to either the front or side of the vehicle. If your vehicle came equipped with a TAC system and if it was removed and replaced with an open-type design air filter/intake assembly, the vehicle will fail the visual emissions component inspection.
If the TAC system has been removed and replaced with an aftermarket open-type air filter/intake system, the system will require to be C.A.R.B (California Air Resources Board) approved. C.A.R.B. approved systems are issued an E.O. (Executive Order) No. and this information is printed on a label, which must be attached in a readily visible location under the vehicle’s hood.