DEC Catalytic Converter (50 state)-Right (cyl# 1-4) - 540i (97-9/98) & 740i/il (96-9/98) - This latest version has 3x the amount of noble metals (platinum, paladium, & rhodium) compared to the previous 49-state version and passes all the OEM tests for the state of CA. In addition, the new "cylindrical" shape is the same as the factory part and fits better to the exhaust tunnel than the 49-state "pancake" shape unit.

Great value compared to the original BMW part....factory like performance and durability with 5x the warranty (Full 5yr with this DEC part vs 1yr BMW warranty), no core requirement, and pricing less than 1/2 of the current factory retail. Ultimate Garage recommends this unit for all 50 states.

Clamping sleeves and Seal Rings should be purchased with the converter as part of the installation to connect the cat to the manifold and muffler assembly.

DEC requires that oxygen sensors be replaced with the converter to ensure warranty protection. Both the Monitoring Oxygen Sensors (before the cat) and Regulating Oxygen Sensors (after the cat) are available at significant savings through the online store.

Shipping - hardware and gaskets (if selected) will ship from NJ via Fedex ground (see transit time map) . Catalytic converter will ship directly from DEC in CA. Expedited delivery options are available at additional cost.

Fitment - DEC catalytic converters are engineered and built to be "direct fit" replacements of the factory units. Occasionally, some of the longer catalytic converters (eg, 5-6' in length...BMW E36 3 series, E39 5 series, etc) may become "tweeked" in transit through rough handling. A 1/4" movement at one end can result in a 3/4" to 1" fitment/alignment issue at the other end. Should this occur, a steel prybar can be used to force the head-pipes into alignment with the manifolds and the back end can be pulled (plenty of leverage here) to align with the muffler. If any damage were to occur to the cat during this process, it will be covered as part of the factory warranty. In the event that a fitment problem is not correctable with reasonable force, please contact me for further recommendations and action.

Additional comments - The most common reason for replacing an OBDII converter is a PO420 code ("Catalyst Inefficiency"). This is caused when the rear oxygen sensor(s) detect a fluctuation that is greater than the vehicle's computer allows. The oxygen sensors do not measure Hydrocarbons, Carbon Monoxide, or Nitric Oxide.....they only measure the oxygen retention of the catalyst. If there is any type of air leak, it could trip this code. DEC has also found that using a higher octane fuel than the manufacturer recommends can cause red light problems. It will cause too much carbon to be built up and trip the PO420 code. CARBON BUILD UP is a major problem. Carbon releases oxygen and will give an incorrect oxygen sensor readings causing the air fuel mixture to be incorrect. This also causes more carbon to build up because of the incorrect fuel mixture. Carbon needs to be cleaned out to maintain proper air fuel mixtures!

Warranty Exceptions - Vehicles that have had aftermarket (ie, "performance") fuel management software changes may experience premature failure of the catalytic converter. This may result in the failure to pass state smog testing. DEC will inspect all cats returned for warranty replacement to determine if there was a "manufacturing" failure. If the failure was due to engine or fuel management issues, they will typically provide a "one-time only" courtesy warranty replacement. Customer is responsible for all shipping (inbound and return) and labor costs on all warranty replacements.