Multiple exhaust indication malfunctions??? | FerrariChat
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Multiple exhaust indication malfunctions???

Discussion in '348/355' started by W Clark, Aug 22, 2015.

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  1. W Clark

    W Clark Rookie

    May 3, 2014
    20
    Colorado
    #1 W Clark, Aug 22, 2015
    '99 F355: All four "Oxygen Sensor Slow Response" codes repeatedly come up. With DashCommand ODBII Ap I can see the O2 Sensor voltages cycle up and down just like they're supposed to. I have to believe this is a indication malfunction. I am ALSO getting the flashing "Slow Down" light intermittently. It will sometimes come on immediately after starting the car. Sometimes I will shut down while it is flashing, let the car sit for hours, and when I restart, the light starts flashing immediately. It will flash from 10 to 15 minutes total, while driving, and then go back out. I have to believe this is also an indication malfunction.
    Now ..... I am hearing that these exhaust system voltages and temperatures route through an additional computer module on their way to the ECM. And my closest Ferrari dealer says this module fails often enough that they keep them in stock.
    Question: What is this thing called and where is it located? I wonder if Ricambi sells em.
     
  2. drbob101

    drbob101 F1 Rookie
    Owner Silver Subscribed

    Nov 26, 2012
    3,821
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    #2 drbob101, Aug 22, 2015
    The O2 sensors and the SDL are seperate and unrelated. Don't confuse them.

    If you're getting CEL related to O2 sensor readings then go through your sensors carefully and eliminate that

    If you are getting SDL then your exhaust gas temp system has issues. The SDECUs, there are three of them on OBDII cars, are probably what you are referring to. They can be buggy and will need to be replaced if so snd Ricambi and others sell yh. You may also have faulty thermocouples as well. You need to troubleshoot the SDL system to figure out what is wrong there.

    The SDL is a stand alone warning system that does have a shut down fail safe mode so even if you don't have high cat temps and your SDL are from a buggy system , you best fix it so it doesn't progress into a bank shut down mode.

    Lots of threads on here on both issues.
     
  3. W Clark

    W Clark Rookie

    May 3, 2014
    20
    Colorado
    #3 W Clark, Aug 22, 2015
    Hmmm, now I'm more confused than ever. The Ferrari of Denver shop says both these pretty obvious errant malfunction indications are logically explained by a computer module that the signals route through that is known to them to fail with significant regularity. It sounds like you are disputing the logic of this suspicion. If I need to troubleshoot the SDL system, I have no earthly idea how to go about it. I am apparently WAY over my head.
     
  4. Rice-Racer

    Rice-Racer Formula Junior

    Jan 10, 2015
    252
    #4 Rice-Racer, Aug 22, 2015
    Well, how about start with letting us know the codes you get?
     
  5. Enzojr

    Enzojr F1 World Champ

    Dec 12, 2013
    14,001
    West of PDX
    Full Name:
    Tomy
    #5 Enzojr, Aug 22, 2015
    Same thing I was thinking, which codes on which side ?
    Or are they the same or different.
     
  6. W Clark

    W Clark Rookie

    May 3, 2014
    20
    Colorado
    #6 W Clark, Aug 23, 2015
    All Four "Oxygen Sensor Slow Response" codes:
    P0133 O2 Circuit Slow Response (Bank 1, Sensor 1)
    P0139 O2 Circuit Slow Response (Bank 1, Sensor 2)
    P0153 O2 Circuit Slow Response (Bank 2, Sensor 1)
    P0159 O2 Circuit Slow Response (Bank 2, Sensor 2)

    But the real question is: Is it true that the voltages from these sensors pass through a separate computer module prior to going to the Engine Control Module? And do the overheat signals from the catalytic converters also pass through this module? Ferrari of Denver says YES ..... and that this module fails often enough that they keep it in stock.
     
  7. mr1233

    mr1233 Rookie

    May 29, 2012
    48
    UK
    Full Name:
    Richard
    #7 mr1233, Aug 23, 2015
    As you've got all four sensors reported there, it suggests that there is something else amiss really. Perhaps a bad earth or some other bad connection but I'm only speculating. I don't think it's an indication malfunction; the ECU is reporting that having adjusted the fuel based on the existing O2 reading, the O2 reading isn't changing as fast as expected. I guess there are other reasons why this could happen. An air leak would seem to be a strong possibility especially since this would also cause high catalytic converter temperatures.

    With regard to the slow down light, as already mentioned this is an entirely separate system. On each side of the car there is a thermocouple, which is connected to a Cat ECU, and the Cat ECU is in turn connected to the main Motronic ECU. It is these Cat ECU's that fail often, and they cause the slow down light to come on - usually intermittently.

    I'm not aware of any O2 sensor codes being generated as a result of a faulty Cat ECU, but as I already mentioned there is a possible link between the two systems if there is an air leak.

    Have a look here for a fuller explanation:
    Ferrari 355 Buyer's Guide - CAT ECU's explained
     

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