This 535i/635CSi catalytic converter is a direct replacement for the original cat and is approved for use in 46 states. Each vehicle model has its own unique emissions requirements and DEC designs and engineers each piece to be a true replacement cat. Unlike cheap aftermarket cats that may not even be legal in your state, DEC cats meet either EPA or CARB emissions requirements for performance, quality, durability, and warranty. DEC has been a market-leader in OE-reproduction catalytic converters since 1984.
DEC does not sell you a universal cat. This is a direct replacement for 1985-1988 E28 535i, 1985-1987 E24 635CSi and includes stainless steel mandrel-bent piping, flanges, and connections. You can use all of your OE hardware and gaskets. This is an aftermarket piece priced significantly lower than the Genuine BMW equivalent. Although Genuine BMW will be a higher quality overall it comes with a price tag typically 3-5x higher. DEC EPA-approved cats have a 2 year or 25,000 mile warranty on the catalytic material and a 5 year or 50,000 mile warranty on materials and workmanship.
Catalytic converters rarely fail on their own. In most cases, another issue has caused the catalytic material to be contaminated, overheated, or damaged, leading to failure. The most typical failure comes from a failed primary/front O2 sensor, which cause the engine to run rich (reducing fuel economy), which also melts the catalyst. Replacing your failed catalyst without solving the root cause of failure will void any warranty and significantly reduce lifespan of the replacement catalyst. It is the customer's responsibility to diagnose and determine the root cause of a catalyst-related engine code. Before spending thousands of dollars on a new catalytic converter, make sure you have considered and investigated all other potential sources for your fault codes - oxygen (O2) sensors, cooling system, intake or exhaust leaks, fuel injection, vacuum, secondary air system, and other emissions-related equipment. Returns of this product are limited to quality and workmanship issues only.
Federal vs California Spec. Catalytic converters must be matched to the vehicle build specification and/or the region where it will be used. Using a non-California cat on a California-spec car will result in failure of emissions inspection and possibly even poor drivability, fault codes, and a check engine light for incompatible parts. Your vehicle spec can be found on an emissions label on the underside of your hood. California-spec cats are more expensive but have premium catalytic material and a longer warranty.
California: you must use a California-spec cat. A California-spec cat can be used in all 50 states, regardless of original spec.
Colorado, Maine, or New York: state law requires a CARB-certified cat for all new sales beginning January 1, 2023, regardless if the car was built as a “California version” or not. The previous "OEM grade" will no longer be accepted in these states.
All other states (Federal): the “Federal” spec is acceptable, however, using a non-California cat on a California-spec car may cause poor drivability, fault codes, and a check engine light for incompatible parts.
E28 (82-88) > 535i
E24 (77-89) > 635CSi