DEC Catalytic Converters - 540i (-2/94) - Left Side

Affordable replacement catalytic converter for states that do NOT use California Emissions

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DEC Catalytic Converters for your E34 540i (1993 to 02/1994 production) are an affordable aftermarket alternative to the very expensive Genuine BMW catalytic converters, which can cost 2x to 5x that an aftermarket part. If your last converter lasted only 2-3 years, it's time for you to consider a higher quality replacement. DEC's heavy-duty machined flanges and mandrel-formed pipes make these acoustically-tuned pieces true factory replacements. 

The catalyst case is 100% stainless steel for maximum durability, and they're covered with a 2-year/25,000-mile internal and 5-year/50,000-mile shell warranty. 

  • Top quality AND affordable
  • Heavy-duty machined flanges
  • Mandrel-formed pipes
  • Acoustically tuned
  • Federal and CARB-legal versions
  • Made in USA
Note: This is the LEFT side converter only - should be replaced in pairs.

Catalytic Converters ("cats") are heavily regulated and laws are different depending on where you live in North America. Multiple states are able to use cats that meet federal EPA standards. California, Colorado, Maine, and New York share a certification commonly known as CARB-approved or 50-state legal. There are specific differences in the catalytic compounds between them. All states can use the more-expensve CARB-approved cat but CA/CO/ME/NY cannot use the federal cat. If your car is a SULEV-spec it is best to use the CARB-approved cat (SULEV models were sold in California, Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington state). This info is accurate as of January, 2021 but state laws may have changed since this posting.

BimmerWorld note on BMW catalytic converters:
  • Fitment - This is an aftermarket piece priced significantly lower than the Genuine BMW equivalent. We prefer Genuine BMW for the perfect factory fit, but with a price tag typically 3-5x higher, we will often install these quality aftermarket units instead.
  • Check Engine Lights and Codes - Replacing your catalyst may not resolve a code for an issue that possibly has another root cause. It is the customer's responsibility to diagnose and determine root cause of a catalyst-related engine code.
  • O2 Sensors - The most typical failure of a catalytic converter is failure of the primary/front O2 sensors, 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 warranty and significantly reduce lifespan of the replacement catalyst.

  • BMW Fitments:

    5 Series
    E34 (89-95) > 540i
    7 Series
    E32 (88-94) > 740i
    E32 (88-94) > 740iL
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