Results 1 to 6 of 6

Thread: E46 Cat. Converter Removal

  1. #1
    Join Date
    Jul 2007
    Location
    Tempe, Arizona
    Posts
    212
    My Cars
    E36 M3, E46 M3

    E46 Cat. Converter Removal

    If I remove the Cats on an E46 M3, do I need the O2 sensor simulators? Or can I just remove the cats and call it good? I know many places sell O2 sensor simulators for the E36 M3 and other cars, but I haven't seen anything for the E46. Thanks!
    NASA Arizona/SoCal - TTC #72

  2. #2
    Join Date
    Feb 2005
    Location
    San Diego, CA
    Posts
    6,533
    My Cars
    S54 and S62
    You can do that and call it good. The car will eventually throw catalic converter ineficiency codes which will trigger the SES light, but not a biggie imo.
    Current:
    Alpine White E46 325i Touring S54 6MT
    Titanium Silver E39 540i Touring M-Sport S62 6MT

    Past:
    Alpine White E46 330i ZHP Sedan S54 6MT
    Interlagos Blue E85 Z4 M Roadster 6MT
    Le Mans Blue E92 M3 6MT
    Japan Red E46 325i Touring S54 6MT
    Estoril Blue Individual E46 M3 Coupe 6MT
    Cosmos Black E36 M3 Coupe S54 6MT
    Alpine White E92 M3 6MT
    Alpine White E90 M3 6MT
    Laguna Seca Blue E46 M3 Coupe 6MT
    Jet Black E36 325is S52 5MT
    Lagoon Green E36 325is 5MT

  3. #3
    Join Date
    Oct 2006
    Location
    IL
    Posts
    12,204
    My Cars
    '01 M3 , '11 X5 35D
    I disconnected my secondary O2 sensors when I put in my headers.

  4. #4
    Join Date
    Jan 2009
    Location
    Ventura County, CA
    Posts
    16
    My Cars
    2004 Imola Red M3
    You can always get a Conforti Shark set up for Euro headers and no cats. If you gut the cats on the US S54 motor, this is essentially what you end up with.

    When the second 02 sensor is left in place with no cats, the ECU will not see the proper voltage variation between the forward and rear O2 sensors. It throws a fault code because it does not know whether something is wrong with the cat (remember, the ECU thinks it is still there) or the O2 sensor. In other OBDII vehicles, I believe that the ECU reverts to closed-loop mode for the O2 signal and just starts using default maps to help control the A/F ratio.

    Shark Injector or D/A Race program would be a more comprehensive work-around.

  5. #5
    Join Date
    Oct 2006
    Location
    IL
    Posts
    12,204
    My Cars
    '01 M3 , '11 X5 35D
    Quote Originally Posted by m5guys View Post
    In other OBDII vehicles, I believe that the ECU reverts to closed-loop mode for the O2 signal and just starts using default maps to help control the A/F ratio.
    As far as BMW ECUs go, they don't revert to closed-loop unless the primary O2 sensors aren't sending the proper voltage.

  6. #6
    Join Date
    Dec 2017
    Location
    Southern Zambia
    Posts
    78
    My Cars
    320i M-Sport 2003 E46
    Hi,
    What did you learn concerning the Cat converters?

    Is it safe to just remove the Cat and dissconect the post cat O2 sensors?

    Thanks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •