(need help!) 360 Modena not "Emission READY" for Smog Check & CEL: P0431 code | FerrariChat

(need help!) 360 Modena not "Emission READY" for Smog Check & CEL: P0431 code

Discussion in 'California (Southern)' started by OceanSide760, Dec 6, 2020.

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  1. OceanSide760

    OceanSide760 Karting

    Jul 8, 2009
    185
    #1 OceanSide760, Dec 6, 2020
    My 2003 360 not "Emission READY" for Smog Check & throws CEL for P0431 [reads: generic, Warm Up Catalyst Efficiency Below Threshold (Bank 1)] code on OBD II Scanner.

    I have Factory pre-cat (inside honeycomb removed) & Factory catalytic converter.
    ___________________________________________________________________________________
    CEL usually comes out every 40~60 miles during normal driving. So I've did the following:

    1. Drive the car extremely slow (low RPM on local street and mostly 60mph in 6th gear on highway for 152 miles), CEL come out on the 153rd mile mark.

    Cleared to CEL then...

    2. Drive the car extremely slow (low RPM on local street and mostly 60mph in 6th gear on highway for 125 miles.

    No Check Engine Lights but OBD II still shows Emission NOT READY (Yellow Light)
    ____________________________________________________________________________________

    I would like to know how can I get "GREEN LIGHT" to be Smog Check?

    Or do I need to get a new set of Factory Pre-Cat? Or maybe my Factory catalytic converters gone bad?

    Or anyone knows if there's any aftermarket Pre-Car or catalytic converter that can pass the California Smog Check?

    If anyone knows good smog technician can help me in the LA / OC / SD area, please PM me.

    Thank you SOOOOO much in advance for your input.


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  2. Red 27

    Red 27 Formula 3
    Rossa Subscribed

    Feb 2, 2008
    1,001
    San Diego, Ca
    Full Name:
    Dave
    #2 Red 27, Dec 8, 2020
    I have had good luck with "North County Smog and Repair Center" 760-591-4859. They are in San Marcos.
    My mechanic recommended them and I have sent a few Fcar friends there. Scotty is the owner and very helpful.
    Good luck!!
    Dave
     
  3. AD170

    AD170 Karting

    Jul 18, 2014
    78
    #3 AD170, Dec 9, 2020
    I'll take a stab at it. First off, the Feds made a big push to clean up emissions on cold starts when engines run rich and are fairly dirty. This engine must have issues on cold start due to the secondary air system and the Precats, both of which are designed to help on cold starts. The Engine Computer (ECM) looks at the rear O2 sensor when determining if the Cat is performing properly. If the O2 sensor is a flat line the Cat is good, if the O2 sensor is switching back and forth from say, .2V to .8V then the Cat is not storing and releasing oxygen as it should and it is bad. This test is done when certain enabling criteria is met so it may take some time to accomplish. The Precats and the MainCats together work to clean the exhaust, and since you removed one part of the equation the rear O2 is cycling. Some people have had luck with O2 extenders which take the O2 sensor out of the main exhaust stream thereby flattening the voltage. This fools the ECM into thinking the Cat is good.
    My suggestion is to buy a set of good used exhaust manifolds and make sure you have a properly running engine with new spark plugs, clean fuel injectors and replace the ignition coils if they are old. The old saying of "Cats don't commit suicide, they are murdered" means something ruined your cats, as they are meant to last the life of the vehicle.
     
    lkstaack and Red 27 like this.
  4. lkstaack

    lkstaack Formula Junior

    Dec 9, 2020
    252
    San Diego
    Full Name:
    Lars
    #4 lkstaack, Dec 28, 2020
    That's good to know. I've also had positive results with V&T Smog Test Only in Miramar (858-695-3645). My old BMW would pass emissions any day of the week, but fail the visual with eagle-eyed inspectors.
     
    Red 27 likes this.

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