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Catalyst Efficiency Code

Discussion in 'Technical Q&A' started by metaldriver, Nov 29, 2015.

  1. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    My 360 presented me with CEL codes P0422 and P0432, Main Catalyst Below Efficiency Threshold. Scrolling through the ECU for any other codes revealed none. I was prepared to see any of the following, but none were displayed even in history.

    MAF Circuit
    O2 Sensors
    Misfire
    Fuel Trims
    Throttle Position
    Coil Packs
    Air Pump Circuit
    High Catalyst Temperature

    Assuming that because none of the above sensors offered a code, I am proceeding on the basis those end devices, in and of themselves, are operating properly. So what caused the cats to allegedly be “defective”? I surmise one of five possibilities.

    1 – Although the MAF sensors did not throw a code, for good measure I rinsed them with aerosol solvent cleaner. Doubtful this is the true cause, but worth a try.

    2 – A leaky intake gasket would allow more air into the combustion chamber than what the injectors could add gasoline, which would result in a lean air-fuel mixture. However, the cats did not get hot and the LTFT / STFT codes are zero, which indicates to me the gaskets are fine.

    3 – The car has 20k miles on it (previous owners kept it sequestered but I am quickly reversing that trend ;)) so I don’t think the cats are deteriorated to the point of instantly becoming ineffective from one day to the next.

    4 – My understanding it that everything is inputted to the two main ECUs, including what is being monitored by the secondary ECUs. For example, if the security system ECU had a fault, the main ECUs would know about it. Could the two cat ECUs both be bad without the main ECUs knowing about it? That seems to me like a very remote possibility, bordering on double-jeopardy.

    5 – Gremlins came and went because after clearing the P0422 and P0432 codes, the CEL is extinguished and the car drives just as it did before and during the CEL.

    I will take #5 all day long but despite this currently appearing to be the case, I am leaning towards #4. Because both banks each threw a code, I can’t reliably switch the two cat ECUs with each other to verify, so how does one test a cat ECU?
     
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  3. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,103
    Austin TX
    Full Name:
    Brian Crall
    Cat ECU has nothing to do with cat operation. It monitors internal temp and warns of an overheat.

    The downstream O2 monitors cat efficiency. No other components are involved. It does not monitor fuel mixture or heat or MAFs or anything else.
     
  4. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    #3 metaldriver, Nov 29, 2015
    Last edited: Nov 29, 2015
    With my laser temperature gun, the cats were in the low to mid 400s.

    The upstream O2 sensors monitor air-fuel, so if those are happy then this points to #3 or #4.

    If one believes the downstream O2 sensor's output explicitly, that implies my cats are shot but I don't capitulate to that theory just yet.

    The early (black lid) cat ECUs are prone to moisture intrusion, as opposed to the better hermetically sealed newer (green lid) cat ECUs.
     
  5. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,103
    Austin TX
    Full Name:
    Brian Crall
    I tried to tell you it has nothing to do with cat temp. Black ecu, green ecu, it doesn't matter. Those are for monitoring cat heat. That is not your problem.
     
  6. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    #5 metaldriver, Nov 29, 2015
    Last edited: Nov 29, 2015
    I tried to tell you it has nothing to do with cat temp.

    Not very well. Please be specific without a tacit inference.

    That is not your problem.

    Then what is? Simply alluding to poor cat efficiency is not pointing to the root cause, unless that can be stated as being the problem, which you haven't.
     
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  8. brian.s

    brian.s F1 Rookie
    Professional Ferrari Technician

    Nov 3, 2003
    3,761
    Midwest
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    Brian
    If you can tell me how long this piece of string is, I could guess at your solution too. There are numerous diagnostic threads around those codes, putting the car on an OBD monitor might produce some more useful data for a diagnosis/guess
     
  9. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    There are numerous diagnostic threads around those codes

    Yes there are. I searched last night several permutations of words, and came up with 238 threads on CEL codes.

    putting the car on an OBD monitor might produce some more useful data for a diagnosis/guess

    That is how I extracted the P0422 and P0432 codes ... with an OBD-2 monitor. However, knowing the codes (or lack thereof) still requires logical process of elimination to avoid guessing.
     
  10. johnk...

    johnk... F1 Veteran
    Owner

    Jun 11, 2004
    8,684
    New England/FL
    Chances are your down stream O2 sensor(s) needs to be replaced. Doesn't matter that it's a Ferrari or a Toyota. Main Catalyst Below Efficiency errors are commonly due to that O2 sensor. If you believe the cats are ok and there are no exhaust leaks present the downstream O2 sensor is the probable cause. No guarantee, but that is where I would start.
     
  11. brian.s

    brian.s F1 Rookie
    Professional Ferrari Technician

    Nov 3, 2003
    3,761
    Midwest
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    Brian
    A generic monitor will still show the outputs of all the O2 sensors as well as many other data streams, the SD/Leonardos are not some magic box that spews out the exact problem, we still read and analyse the numbers to arrive at a conclusion, right or wrong. I have a 550 currently giving strange numbers on both secondary sensors, this suggests they are faulty.
     
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  13. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,103
    Austin TX
    Full Name:
    Brian Crall
    Failing O2 sensors are too often intermittent for me to spend much time trying to catch them malfunctioning. If I get an error related to O2 or possibly caused by an O2 it gets replaced before any further diagnosis. It has saved countless hours chasing windmills. O2 have become Kleenex parts based on their quality and the sensitivity of the Motronics observation of operation.
     
  14. Dave rocks

    Dave rocks F1 World Champ
    BANNED

    Nov 23, 2012
    15,969
    Orchard Park, NY
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    Dave Lelonek
    Please realize, you may have a bad CAT and that is the reason for the code - it's not doing it's job. I had the exact issue this year and upon inspection the CAT was toast.

    New CAT's and all is well.
     
  15. INTMD8

    INTMD8 F1 Veteran
    Owner

    Jun 10, 2007
    5,635
    Lake Villa IL
    Full Name:
    James Moran
    They can deteriorate over time until they are inefficient enough to cause a catalyst code, doesn't mean it happened overnight. Should be easy to tell by comparing primary and secondary o2 waveform.
     
  16. rotaryrocket7

    rotaryrocket7 Formula Junior

    Dec 7, 2011
    482
    Eden Prairie, MN
    Full Name:
    Matt
    All other feedback is good... I am dealing with the same issue (CEL 420), and will replace downstream O2's first. If I wanted to validate before I would:
    1- monitor live data on O2 and see what's happening on primary vs. secondary through OB2 feed( not perfect due to lag, but you can get a sense), then I would use laser temp gun to monitor temp going into cat and then out of cat. If temp is dropping from in to out the cat is probably bad, if it's going up, the cat is working.

    From a timing perspective, I would replace O2's first and then monkey around after as Brian had suggested.
     
  17. Falcon Wing

    Falcon Wing Formula 3

    Aug 4, 2010
    1,248
    Colorado Springs
    I get the P0432 Cel sometimes too. (01 360 Spider)

    I have a couple questions:

    1. The Cel seem to come up rather inconsistently, but at times shows up when I am under quick acceleration that is not sustained, like when passing a car. Could the CEL be a result of unburned fuel burning in the CAT?

    2. Sometimes when I see the CEL, I will pull over, check the code, clear it, then continue. The code NEVER seems to appear again for the rest of the day, and I notice no difference in performance. Is it possible what ever triggered the CEL is instantaneous, meaning just enough to trigger?

    2. I'm currently running stock headers/cats into a TUBI exhaust. I have FABSPEED headers/blankets, hyper flow CATS w/ Fabspeed 02 extenders that I have yet to install. Is it possible the newer components may rid me of the p0432 CEL?

    Thanks....I been wondering about these questions...
     
  18. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    I disagree with that approach, because my codes do not support this action and simply replacing the O2 sensors “because it is easy” is not a prudent way to begin the diagnostics procedure. The codes are always real for the simple reason that they indicate a pending or stored unexpected parameter(s). Not always clear is what triggered the codes. Diagnostic skills are still required, despite the miracles of the internet. There are other scans which can be performed that confirm or deny an O2 sensor being at fault. The complication lies in the fact that dirty grounds or bad connections or broken wires can result in intermittent transfer of sensor data or adulterated data.

    The preponderance of evidence and lack of any other codes suggests my cats are the intermittent culprit. This past week I had a Stradale muffler installed, which provided the perfect opportunity to inspect the cats. The cores were intact with no visual signs of mechanical damage.

    Before the muffler installation I performed some datalogging, specifically comparing the output voltage of the up-stream-downstream O2 sensors. To prepare the cats, I drove the car for twenty miles in city and on highway. During the test I averaged 70 MPH for almost ten of those miles, varying throttle position to affect change. The upstream voltage fluctuated from 2-700 mV (as you would expect in closed-loop mode, so the ECUs can make adjustments in search of the constant 14.7:1 air-fuel ratio) and the downstream voltage was 4-500 mV. Those are text book voltage displays of working cats … for now.

    We looked at the fuel valves and the secondary air system, with no indication the evaporation system is at fault. A smoke test confirmed there are no gasket leaks anywhere. If the O2 sensors were replaced at the beginning of the diagnostic procedure, that would have proved nothing, except to spend money that is not needed. My conclusion is that because the car has no pre-cats, the main cats are sometimes not up to the task of conditioning the full exhaust flow. They are getting weak to the point that low-speed driving combined with cold ambient temperature upsets the delicate balance of the O2 sensor readings, thus the CELs.
     
  19. johnk...

    johnk... F1 Veteran
    Owner

    Jun 11, 2004
    8,684
    New England/FL
    If you don't want (need) other's advice (help), why bother asking? Obviously it makes a lot more sense to conclude your cats are bad and spend $9k each to replace them with OEM cats than it does to spend $100 for an O2 sensor to verify they are not the culprit. Of course, with no pre-cats neither may correct the CEL problem.
     
  20. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    #17 metaldriver, Dec 11, 2015
    Last edited: Dec 11, 2015
    I asked for opinions of what may be the cause of an issue. I am not obligated to agree with everyone’s input. Is it so bad that I don’t follow the alleged fix in a manner they prescribe? One of the main uses of the forum is to share information, and to use feedback as we see fit.

    I don’t know where you get the idea of me spending $9000 each on cats, but that is quite laughable, when there are any number of good manufacturers offering cats for $2-4000 for both.

    Your contention is that if there are no air leaks, to begin with the downstream O2 sensor, based on the assumption the main cats are not faulty. That is an anecdotal method. Being an engineer, I work off of facts. In your own words (post # 8) was the statement that replacing the downstream O2 sensors is no guarantee of fixing the problem. I simply chose to not follow that advice.

    Oh, and one of the elder statesmen who alleges he told me what the problem is with my car? He didn't, unless I am expected to be an expert in mind reading.
     
  21. rotaryrocket7

    rotaryrocket7 Formula Junior

    Dec 7, 2011
    482
    Eden Prairie, MN
    Full Name:
    Matt
    Sounds like you took a very thorough approach, and even saved from replacing working O2 sensors.

    One question though, since you haven't actually diagnosed it at this point, couldn't it just as well be an intermittent failure of the O2 sensor as well?

    I think Brian's point, which I agree with, is that intermittent failures of O2's does happen and chasing them is time costly, if book time is roughly $140 an hour, than simply replacing them is going to cost about an hour's worth of chasing the problem. Probably comes down to time vs. money, which do you want to invest.

    I applaud the approach you've taken, it's undoubtedly the "right" way, my approach would have been slightly more biased to time, but in the end it could backfire (if your assumption about the actual root cause it right).
     
  22. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    #19 metaldriver, Dec 11, 2015
    Last edited: Dec 11, 2015
    You are spot on about an errant O2 sensor being a challenge to properly diagnose if there are loose connections. I like to tinker with my car, so my sweat equity labor is free. FoH's shop rate is $165, so your point is well taken. If the cats act up very infrequently I can clear the P0422 and P0432 codes in thirty seconds. The purists may call that blasphemy, but I call it pragmatic to avoid new cats.
     
  23. zackspeed

    zackspeed Karting

    Nov 4, 2003
    67
    AZ
    Full Name:
    Zack
    You have bad cats. The only thing that causes these errors are bad cats. The ecu needs to see very specific data from many different sensors before it will trigger this code. The root cause is worn out aged cats. Pretty common on those cars now. And the only cure is new ones. Don't bother with any of the aftermarket ones either. They are a waste of money.
     
  24. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,265
    USA
    Full Name:
    Hugh G. Rection
    The Motronic is very sensitive to catalyst performance. Most of the aftermarket catalysts will eventually throw low efficiency codes. Sometimes within 50 miles, other times within a few thousand. Occasionally, you can get lucky...hopefully that will be you if you choose to go that route.
     
  25. metaldriver

    metaldriver Formula Junior

    Apr 6, 2015
    612
    Houston, Texas
    Full Name:
    Andy Vecsey
    #22 metaldriver, Dec 12, 2015
    Last edited: Dec 12, 2015
    Don't bother with any of the aftermarket ones either. They are a waste of money.

    The Motronic is very sensitive to catalyst performance. Most of the aftermarket catalysts will eventually throw low efficiency codes.

    What is the basis of putting a 600-cell factory cat superior to a 200-cell aftermarket cat? The latter will have less back-pressure; however, lower cell density doesn’t necessarily mean the cat is less effective at converting exhaust gases.

    The key here is what material is in factory cats versus that of aftermarket cats. Websites for aftermarket cat manufacturers often advertise what they use in their cat core, which I have not seen from Ferrari.
     

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