You must replace the existing catalytic converter with a CARB (California) approved CAT designed and manufactured for your BMW 318i; even though your vehicle is out-of-state emissions certified. A smog check repair technician will suggest purchasing the new catalytic converter from the BMW dealer, as the dealership will not risk selling a non-California approved CAT.
There is much confusion regarding the use of non-CARB catalytic converters as replacements on out of state (Federal 49-state) emission certified vehicles. The fact is however, in 2009, the California Air Resources Board banned the use of non-CARB complaint emission components, regardless of a vehicle's emissions configuration, if the vehicle is being operated in California.
posted by SmogTips Support 03-14-2019 02:31 PM