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355 CA smog issue with cats or is it?

Discussion in '348/355' started by diviter, Feb 10, 2019.

  1. diviter

    diviter Rookie

    Apr 2, 2009
    16
    I am reaching out to the community in the hopes that someone else has had the same issues and found a solution.

    I recently purchased a '97 355 with a well documented service history. I drove the car home over 70 miles and all was good (no CEL).

    In July 2018 the cats were changed by the previous owner and the car passed smog. When I purchased the car it had to be tested again because more than 90 days passed. The car passed the sniffer but the ECU had codes so it FAILED. I took it to a local mechanic that works on Ferraris and he checked the codes which showed catalytic failure on both banks. Since the emissions were OK we decided to reset the codes and try to drive the cycle to clear the ECU.

    I drove about 30-40 miles and then the CEL came on. We installed extenders to the oxygen sensors and tried again but the CEL came on again. We changed the cats and the CEL came on again. Previously there were numerous pending codes but now just the catalytic is failing on both banks. No oxygen sensor codes now.

    We are unsure what to do next. The mechanic is a bit perplexed as both banks always seem to fail at the same time. Is there a bigger problem?

    Thank you in advance for taking the time to read this and I hope that someone else has had a similar issue and found a solution.
     
  2. Ferrarium

    Ferrarium Formula 3

    Jul 28, 2018
    1,692
    Central NJ
    Full Name:
    Eric
  3. Drock28

    Drock28 Formula 3

    Jan 13, 2013
    1,328
    Montreal
    Full Name:
    Tony
    perhaps the actual o2 sensors themselves have an issue.
     
  4. bcar1

    bcar1 Karting
    Silver Subscribed

    Aug 2, 2017
    52
    NYC/NJ
    Full Name:
    Bob
    What is the exact codes now & what was pending before? Any sdl? I was having a similiar issue from a miswired tcu that drove me nuts. I never got that far but replacement pre/post 02 sensors are cheap and worth a shot.
     
  5. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,461
    San Carlos, CA
    Full Name:
    Mitchell Le
    exact codes would help.
     
  6. johnk...

    johnk... F1 Veteran
    Owner

    Jun 11, 2004
    7,586
    New England/FL
    If it's a cat efficiency code 99/100 time it the post cat O2 sensor. Any decent mechanic will tell you that.
     
  7. Ferrarium

    Ferrarium Formula 3

    Jul 28, 2018
    1,692
    Central NJ
    Full Name:
    Eric
    Its a bit worrisome that the mechanic scratches his head on this to be honest....
     
  8. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,461
    San Carlos, CA
    Full Name:
    Mitchell Le
    Can you tell us more data?
    What brand cat converters?
    What exact error codes?
    What kind of extenders and where ?

    In my experience with many 355s, nothing beats a set of working factory cats for passing Smog.
     
    taz355 likes this.
  9. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,144
    Austin TX
    Full Name:
    Brian Crall
    Exactly. If you have to search the internet for a solution to this problem you are bringing the car to the wrong guy.
     
    taz355 likes this.

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