P0421 / P0431 Trouble Codes (Catalytic Converter) ... anyone have good fix?

Discussion in '360/430' started by bisel, May 25, 2017.

  1. ferralc

    ferralc Formula 3
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    I am pretty sure this setup will work, what is an “extended period”?


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  2. bisel

    bisel Formula 3
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    It has been 16 hours now. I was going to drive today but looking like tomorrow now. So that will add another 14 hours or so

    Steve
     
  3. ferralc

    ferralc Formula 3
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    You will be good with the extra extender you will see



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  4. bisel

    bisel Formula 3
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    It has been over a week. Several shorter drives with cumulative total of about 200 miles. No codes yet. I am hoping it stays that way.

    Steve
     
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  5. whatheheck

    whatheheck F1 Rookie
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    That's great news.

    Thanks for the update Steve.

    Dan
     
  6. bisel

    bisel Formula 3
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    Just this morning I was thinking that I resolved the CEL issues ... when, just pulling into the street where I live, the CEL comes on. Damn! And I was feeling so confident.

    Pulled out OBD reader and the code is different now ... I was always getting P0421 or P0431 (usually both and they are the same code but for different engine banks). Today, I got P0159 ... "O2 Sensor Circuit Slow Response Bank 2 Sensor 2". Potential things to check include:
    • Check the wiring
    • Check the signal (0.97-1 .OS)
    • check fuel injector and wiring
    • Check ignition coil and wiring
    • Check engine CO HC emission base HC<250ptunCO<I.l%
    In checking online, there seems to be a school of thought that if the engine is running OK, to just replace the O2 sensor. Anyone here have any experience with this code?

    Thanks,

    Steve
     
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  8. cpep

    cpep Karting
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    You can try swapping them from side to side and see if the code follows. If it does then change the sensor. If not then its too far out of the air stream. I cant believe your still having these issues with all you have done. I have basically the same set up and after a 15min drive I only have the evap left to satisfy.
     
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  9. bisel

    bisel Formula 3
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    When I was young boy, I once talked back to my mother. That may be the root of all these problems.

    Steve
     
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  10. cpep

    cpep Karting
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    You will figure it out eventually. Mothers don't hold grudges.:)
     
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  11. whatheheck

    whatheheck F1 Rookie
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    Sorry to hear that Steve.

    And Im sorry I cant offer any solution.....

    I hope you figure it out soon.

    Dan
     
  12. G. Pepper

    G. Pepper F1 Veteran
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    That's interesting. So the Fabspeed Sport Cats are designed to take 100% of the cat cleaning duty, theoretically eliminating the need for the pre-cats. I believe I'll instal the Sport Cats first then, and see how that goes.
     
  13. StickBreitling

    StickBreitling Formula Junior

    Oct 12, 2012
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    Sorry to divert and hijack the thread slightly. My set up consists of AP headers, 200 cell sports cats and a Kline exhaust. After getting 420/430 codes and reading the thread, I installed Fabspeed mini cats with straight extenders. Previously the code would come on within 50 miles of driving. After installation of the mini cats, the CEL would come on after 300 miles. I've tried clearing the codes and also disconnecting/reconnecting the battery. When the CEL comes on it always throws up both 420 and 430 (cats below efficiency). The car drives with zero issues.

    Not sure what else to try:
    - go back to original cats
    - try another set of 200 cell cats
    - longer disconnect of battery
    - o2 sensors (not sure this is of any value as both codes are thrown simultaneously)
    - ECU tuning
    - live with it
    - get a specialist to diagnose
     
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  15. cpep

    cpep Karting
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    I would say original cats would solve your problem. Never had any luck with aftermarket high flow cats.
     
  16. bisel

    bisel Formula 3
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    I have stock cats and am still getting codes. But, the latest code is a bit different that prior codes. Recall in my prior postings that after replacing the stock headers with aftermarket headers, I started getting P0421 / P0431 which states that the downstream O2 sensor is detecting that the converter is not working properly. Now, since I removed the stock headers with their pre-cats, one would conclude that the main cats are likely working OK and what has occurred is that amount of catalytic material between the upstream and downstream O2 sensors is less than before, so the ECUs determined that the cats were not up to snuff.

    So, to resolve that issue, I installed O2 extenders and a mini-cat on both O2 sensors. And ... based on this new code (i.e., P0159) it seems that the O2 sensors are not "detecting" that there is a problem with the catalytic converter efficiency. But something different.

    What the ECU is sensing, code P0159 ... is that the O2 sensor has a slow response time. I was talking to a knowledgeable Ferrari tech this morning and to summarize some of his points ... If you blip the throttle and simultaneously monitor the upstream and downstream O2 sensors, you will see an immediate response from the upstream sensor and lag in the response from the downstream sensor. Perfectly normal. But, now that I have the O2 sensors further out of the exhaust stream, the downstream sensor is likely lagging further behind than it was before. By the time it does respond, the elapsed time is beyond the threshold that the ECU is looking for. He also advised me that with 14 year-old sensors, it is probable that the O2 sensor is aging and not responding as quickly as a new sensor might. As he explained it, this is also normal for aging sensors.

    So, my next strategy is to get two new downstream O2 sensors. I will reset adaptive parameters and install the new sensors and try again. I will update this with results as they become known.

    Steve
     
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  17. RedTaxi

    RedTaxi Formula 3

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    ^^^ Extenders restrict the amount of gas getting to the sensors. Mini cats will do the same. I would try with just the extenders. Worked for me after throwing cat codes with de-cat headers. 2 years on now.
     
  18. Carnut

    Carnut F1 Rookie
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    I have Fabspeed headers and cats on my 430. It took about 20 miles for the check engine light to come on. I am trying to get the software to download into my tablet (I really hate computers) so I can read the codes to Algar. Car seems to be running fine.
     
  19. mkzhang

    mkzhang Formula Junior
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    I too had the slow response time CEL.

    It's pretty much your mini cat and extender not working. It's doing a good enough job that at idle by not triggering a CEL, but when you give it gas it's not able to scrub the exhaust fast enough for the signal to go back down to the threshold soon enough. Hence the CEL.

    A good way to test this is to loosen your o2 sensors, then you will get a low efficiency CEL as it's getting too much clean air.

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  20. mkzhang

    mkzhang Formula Junior
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    Double post--.


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  21. bisel

    bisel Formula 3
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    I purchased a pair of Bosch O2 sensors for the downstream location. When I receive them I will install and try working with the extender / mini-cat combination

    Steve
     
  22. StickBreitling

    StickBreitling Formula Junior

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    I did have the set up with extenders only, but that also threw up the 420/430 codes. Adding the mini cats throws up the same codes, but it takes longer before it happens.
     
  23. Carnut

    Carnut F1 Rookie
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    I was able to read my codes yesterday, and I was surprised P0477, P1602, & P0133. The 0477 is Exhaust by-pass valve (low input), it is saying absent. I am using Steve's kit with the button installed in my ashtray. I am not getting the 420/430 code.
     
  24. Sean F.

    Sean F. F1 Rookie

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    The EU cars do not have the pre-cats and work just fine. What is different about the EU cars vs US cars that they work fine with out the pre-cats? ECU programming?
     
  25. G. Pepper

    G. Pepper F1 Veteran
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    If I may be allowed to throw a wrench into the gears of this thread: My O2 sensors are fine, the ECU's are fine, the headers are fine, the cats are fine, and the CS exhaust is fine. What was happening was intermittent electrical cutouts to the right bank ECU. That's what triggered the CEL and why it was so random as to when it happened. The culprit? I'll quote Clint, my service rep: "Jim tracked the random electrical failures down to a loose pin at one of the wiring harness sockets behind the seats."

    A loose pin. Took six months and four tries to figure that out! At least all the components related to my exhaust are new now. :)

    So, it could be something seemingly unrelated.
     
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  26. Skippr1999

    Skippr1999 Formula 3
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    Great info. How in the World did they find that ??
     
  27. ferralc

    ferralc Formula 3
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    Wow that is a great find
    Electrical gremlins are the most frustrating ones.
    I miss those days when the cars were “simpler”, I have a Testarossa and I was loosing 6 cylinders intermittently the culprit a loose connector on the fuse panel that feeds the fuel pump on that bank. A 30 year old car that barely has electrical components but fuel injection and they go wrong too.
    I think this thread should become a sticky because all the solutions possible have been discussed, and even links to other interesting threads have been posted.




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