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P0420 code - SOS downpipes & Fabspeed Cat Back exhaust

midget fidger

midget fidger

Registered Member
Joined
23 September 2022
Messages
19
Location
Orlando, FL
Just a few minutes after starting the car and hitting the highway, I got simultaneous warnings on the dash. Emissions System Problem and Electronic Parking Brake Problem.

Dealer said it had a P0420 code for the catalytic converter. The car is under warranty, but due to the aftermarket items, they cleared the codes as a courtesy and said I'm on my own. I was hoping they would do more or replace something since Google shows lots of Acura and Honda owners hitting these same two warnings at the same time.

I've had the car for 2 months / 400 miles, and this is the first time it complained. The previous owner had the parts installed at their local Acura dealer, so I suspect it was all done properly. I like the sound and would rather keep things as-is if it's just a warning. No emissions requirements where I live.

Should I just invest in an OBD2 tool and clear this code anytime it shows? Any other recommendations? Thanks!
 
midget fidger said:
Just a few minutes after starting the car and hitting the highway, I got simultaneous warnings on the dash. Emissions System Problem and Electronic Parking Brake Problem.

Dealer said it had a P0420 code for the catalytic converter. The car is under warranty, but due to the aftermarket items, they cleared the codes as a courtesy and said I'm on my own. I was hoping they would do more or replace something since Google shows lots of Acura and Honda owners hitting these same two warnings at the same time.

I've had the car for 2 months / 400 miles, and this is the first time it complained. The previous owner had the parts installed at their local Acura dealer, so I suspect it was all done properly. I like the sound and would rather keep things as-is if it's just a warning. No emissions requirements where I live.

Should I just invest in an OBD2 tool and clear this code anytime it shows? Any other recommendations? Thanks!
Click to expand...
I purchased a 2018 in October. With SOS downpipes with the same issue. I contacted SOS about it but the warranty is for the original purchasing party. But it’s also been on the car over a year. However SOS did offer to recat both units for a REALLY reasonable price. Note: It’s a 12 week lead time. I’ve been a Technician for Honda over 20 years. We do have emissions extensions on certain cars for catalytic converters, fuel injectors and so forth. But once you have aftermarket parts it becomes the owners responsibility. Sadly we don’t have any current Service news/bulletin’s that apply for the NSX to Update the PCM to change the parameters for giving false converter codes like a few other 4 cyl and V6 models have.

Does your car happen to have a SOS JB4 tuner on it? You can check and clear codes with the JB4 and also change your tune for a few more ponies.

On a side note. Did you purchase this car from Karen Radley Acura? I was interested in an orange NSX they had back September.
 
If you go to the web site for Fabspeed and look up the NSX you will see their offerings. Note that they offer the following: Acura NSX Exhaust Valve Simulators (FS.ACURA.NSX.EVS) - $300
perhaps your car does not have these? They recommend for 2019 and up. Often the codes that are thrown are not always so definitive. I have the SOS downpipes with stock exhaust and have never had a error code thrown in the last 11,000 miles and 3 years of ownership.
 
md23vtec, yep, this is the orange 2019 from Karen Radley :) It doesn't have the SOS JB4 as far as I'm aware, but a friend recommended the Autel Autolink AL319. I got it for $32 and successfully cleared the codes. In addition to P0420, it showed P0430 as well. Both related to cats.

drmanny3, I assumed the previous owner got the exhaust valve simulators, but I might as well double check.

Noob question...are there cats on both the SOS downpipes and Fabspeed exhaust, or just the downpipes? That will help me isolate which company to try asking for a favor.

Thanks!
 
midget fidger said:
md23vtec, yep, this is the orange 2019 from Karen Radley :) It doesn't have the SOS JB4 as far as I'm aware, but a friend recommended the Autel Autolink AL319. I got it for $32 and successfully cleared the codes. In addition to P0420, it showed P0430 as well. Both related to cats.

drmanny3, I assumed the previous owner got the exhaust valve simulators, but I might as well double check.

Noob question...are there cats on both the SOS downpipes and Fabspeed exhaust, or just the downpipes? That will help me isolate which company to try asking for a favor.

Thanks!
Click to expand...
I believe it is just the downpipes but don't quote me. :)
 
midget fidger said:
md23vtec, yep, this is the orange 2019 from Karen Radley :) It doesn't have the SOS JB4 as far as I'm aware, but a friend recommended the Autel Autolink AL319. I got it for $32 and successfully cleared the codes. In addition to P0420, it showed P0430 as well. Both related to cats.

drmanny3, I assumed the previous owner got the exhaust valve simulators, but I might as well double check.

Noob question...are there cats on both the SOS downpipes and Fabspeed exhaust, or just the downpipes? That will help me isolate which company to try asking for a favor.

Thanks!
Click to expand...
P0420 is Bank 1 P0430 is Bank 2. Both converters have codes so you need both down pipes. The lead time was 8-12 weeks when I last spoke with them. With it being December and I assume you’re on the east coast it would be an ideal time to take them off and send them back if you want to get them recatted. You can email them directly.

[email protected]
 
I have grp graham rahal exhaust and downpipes on my car and got same codes, my dealer reset for me and then I purchased the fab speed o2 sensor extenders which have a mini cat in them and had my dealer install for me, some have said it is waste of time to add extenders but wasn't expensive and worth a shot for me.. also bc it is not valved exhaust any more I also added the valve plugs to plug into hem harness to tell the car they are attached, I down drive often or really spirited but no codes thus far and probably jinxed myself lol.. hope you find a solution that works for you.
 
SOS said the cats can get clogged from octane boosters or leaded fuel and it could affect efficiency/performance. It's possible octane boosters were used by the previous owner, but they offered to replace the cats for a reasonable price. Only thing is it's contingent on inspection.

So I'd have to find a shop to remove the downpipes, keep the car stored while I ship them to SOS, then get a replacement reinstalled.

Since the codes haven't come back since the last clearing, maybe the clogging is mild and I can procrastinate a bit more!

Interesting info about the Fabspeed O2 Sensor Spacer! That's a pretty clever workaround.
 
Way back when I had my 2001 supercharged NSX I tried running straight exhaust by removing the cat. After a while I had codes appear. The straight cat replacement tube had threaded holes in the front and rear. I added an extension which is placed into the rear sensor opening. It sticks out perpendicular and fools the system in thinking there is a difference between the front sensor and the rear one. It worked. I understand there are some cleaners out there, but not sure they work.
 
So I have a SOS exhaust and cat system. I get the codes, cleared them out, then eventually they come back up. Has Anyone found a solution yet?
 
If you're willing to remove the downpipes and ship them back to SOS, that's probably the best bet. If you go that route, I would make sure to stay away from octane boosters.

I'm talking with someone else who plans to do a setup with no cats at all. Depending how well it works and if the codes can be silenced, I might do the same. Luckily there are no emissions requirements in my state.

drmanny3 said:
If you go to the web site for Fabspeed and look up the NSX you will see their offerings. Note that they offer the following: Acura NSX Exhaust Valve Simulators (FS.ACURA.NSX.EVS) - $300
perhaps your car does not have these? They recommend for 2019 and up. Often the codes that are thrown are not always so definitive. I have the SOS downpipes with stock exhaust and have never had a error code thrown in the last 11,000 miles and 3 years of ownership.
Click to expand...

I took a peek in between the exhaust tips and saw the following. Is this where the valve simulator would plug in? Is the small black thing the valve simulator?

IMG_2564.jpg
 
midget fidger said:
If you're willing to remove the downpipes and ship them back to SOS, that's probably the best bet. If you go that route, I would make sure to stay away from octane boosters.

I'm talking with someone else who plans to do a setup with no cats at all. Depending how well it works and if the codes can be silenced, I might do the same. Luckily there are no emissions requirements in my state.



I took a peek in between the exhaust tips and saw the following. Is this where the valve simulator would plug in? Is the small black thing the valve simulator?

View attachment 177611
Click to expand...
That’s not a connector for the exhaust valve simulator. It’s a factory end intentionally left closed.
 
docnsx said:
I have grp graham rahal exhaust and downpipes on my car and got same codes, my dealer reset for me and then I purchased the fab speed o2 sensor extenders which have a mini cat in them and had my dealer install for me, some have said it is waste of time to add extenders but wasn't expensive and worth a shot for me.. also bc it is not valved exhaust any more I also added the valve plugs to plug into hem harness to tell the car they are attached, I down drive often or really spirited but no codes thus far and probably jinxed myself lol.. hope you find a solution that works for you.
Click to expand...
Did the fab speed O2 sensor extenders worked?
 
Yeyo2021 said:
Were they easy to install or u needed extra parts?. I probably going this route.
Click to expand...
I had it done at my dealer by their nsx tech.. he is very particular and if I remember he said it was pretty straight forward but the orientation was tight if that helps ?
 
docnsx said:
I had it done at my dealer by their nsx tech.. he is very particular and if I remember he said it was pretty straight forward but the orientation was tight if that helps ?
Click to expand...
Great! Tha k you very much. How much did it cost if u don't mind me asking
 
docnsx said:
Lmk if and when rectified if it was successful
Click to expand...
I JUST passed emissions with my car. I haven’t had the codes return yet. As well as two other cars that have had the same issue as well. Since I put extenders on 2 other NC1’s and my own. So far so good. During the same conditions when the cars would’ve normally set the P0420 and/or P0430 codes have not happened since the installs dating from back to November 2022. I’m just giving my personal experience with the extenders so far.
 

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