RM European Auto Parts
Results 1 to 8 of 8

Thread: P0430 with (seemingly) good cat

  1. #1
    Join Date
    Jun 2017
    Location
    Southern MD
    Posts
    3
    My Cars
    330xi 2004

    P0430 with (seemingly) good cat

    I recently got the infamous CES light throwing a P0430(cat bank 2 inefficiency) on my 2004 330xi with 182k miles. I probed the post cat and pre cat sensors using torque pro, and to my untrained eye all readings from the o2 sensors are as to be expected, post cats are steady but react to changes in throttle, and pre cats are oscillating high low as expected. The pre cats dont seem to be too in sync however... Mostly it looks like the bank 2 lags a little but the frequency is the same. Also when I do the test results, sometimes one of the o2 sensors throws an error but i forgot to write it down. I'm not exactly sure what steps to take to be honest, as this is my first car and I am just getting into car mechanics. Any help would be greatly appreciated!!

  2. #2
    Join Date
    Jan 2016
    Location
    Ca
    Posts
    6,981
    My Cars
    2001 525it
    I guess people are using spark plug adaptors to pull the post cats sensors up out of the way then get the car smogged

  3. #3
    Join Date
    Mar 2015
    Location
    west chicago il
    Posts
    509
    My Cars
    01 E46 330i 5sp man spor
    Take care of the o2 sensor issue before replacing a cat. Pre cat sensors won't be synchronized. That is normal. Similar switching frequency is also good. O2 sensor replacement interval is 100k. You are almost double that. Probably a good idea to replace them all.

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  4. #4
    Join Date
    Jun 2017
    Location
    Southern MD
    Posts
    3
    My Cars
    330xi 2004
    I just got the car used(for free from a friend) and he has no idea if the sensors were ever replaced, so the current ones might only have 80k miles or even less. One thing I notices was that the post cats were sitting at around .8volts. Does BMW have a voltage bias, or is it actually that rich? Maybe the air filter needs to be replaced?

  5. #5
    Join Date
    Dec 2004
    Location
    Huntsville, AL
    Posts
    25,923
    My Cars
    87 325is
    The first step is to replace the pre-cat sensors.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  6. #6
    Join Date
    Jun 2017
    Location
    Southern MD
    Posts
    3
    My Cars
    330xi 2004
    I replaced the air filter and no light and the engine isn't running as rich.. we'll see.

  7. #7
    Join Date
    Dec 2013
    Location
    Chicagoland area
    Posts
    4,372
    My Cars
    EXOTICS
    Quote Originally Posted by Elitewill1200 View Post
    I just got the car used(for free from a friend) and he has no idea if the sensors were ever replaced, so the current ones might only have 80k miles or even less. One thing I notices was that the post cats were sitting at around .8volts. Does BMW have a voltage bias, or is it actually that rich? Maybe the air filter needs to be replaced?
    If no one has any idea on when or if the sensors were replaced-REPLACE THEM!
    Better it being the sensors replaced, than cat replacement, due to fuel mixture errors.
    Also makes it difficult to pass emissions, if that is a concern.

  8. #8
    Join Date
    Dec 2004
    Location
    Huntsville, AL
    Posts
    25,923
    My Cars
    87 325is
    Lazy or bad pre-cat O2 sensors will cause the engine to run rich. Which if not corrected by replacing the sensors will eventually cause the catalytic converters to fail from overheating. The post-cat sensors are in a more benign environment and rarely need replacement. So replace the pre-cat sensors now!
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

Similar Threads

  1. E36 wtb: OBD2 midpipe with good cats
    By scooper in forum BMW Parts Wanted
    Replies: 3
    Last Post: 11-02-2011, 08:07 PM
  2. WTB: S54 headers with good cats
    By lotusTT in forum New England - US
    Replies: 1
    Last Post: 03-14-2011, 03:20 PM
  3. I need to borrow obd1 midpipes with good cats socal
    By ultimate99m3 in forum Drivetrain & Transmission Parts
    Replies: 5
    Last Post: 04-26-2010, 08:14 PM
  4. FS: E36 M3 OBD-II Mid-pipe with good cats
    By Topflight in forum Georgia sponsored by Harrison Motorsports
    Replies: 1
    Last Post: 08-02-2009, 06:06 PM
  5. anybody have OBD1 full piping with good cats?
    By oliverr871 in forum California sponsored by Avus Autosport
    Replies: 2
    Last Post: 05-20-2008, 07:32 PM

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
  •