The Broken Fiat Club

QUESTION: Can I get rid of the check engine light after switching to a catless downpipe, or a 200 cell downpipe?
QUESTION: Can I pass emissions if I have a catless downpipe, or a 200 cell downpipe?

TL;DR ANSWER: You can get rid of the light, it's not easy, and no you won't pass emissions.

LONG ANSWER:

When you change the downpipe on a Fiat 500 Abarth, or a Fiat 124, it will throw a CEL, or Check Engine Light, soon after. When you check, you will find it has a P0420 code. You'll want to get rid of this.

SOLUTION FOR NON-EMISSIONS AREA: You can delete the cat code with a flash tune. Any reputable tuner, Tork, EC, Speedmotive, Open Flash, Multiair Tuning & Development, Old School Garage, any of those can delete the code. You will now no longer have a Check Engine Light, and you will not have a P0420 code.

WILL IT PASS EMISSIONS: Chances are it won't. Check your state/local laws. The "deleted" code will appear as "NOT AVAILABLE" when scanned. Most states are wise to this and will fail you the same is if the sensor reads "NOT READY".

HOW DO I PASS EMISSIONS WHEN CATLESS/HI FLOW: You will need to swap your original factory catalytic converter back onto the car, reset the ECU and drive it until the "Not Ready" codes clear. User reports are that this takes a LONG TIME. Some users have had to go more than 1000 miles. Also, running catless can damage the secondary O2 sensor so it may need to be replaced.

MY FRIEND / A FORUM SAID I CAN USE A SPACER TO FIX THE PROBLEM: Success with spacers range from "Temporary success, hurry and get it passed before it throws a code" to "Absolutely worthless". Most owners find spacers are absolutely worthless, as the code will take longer to re-appear, but it will still appear before the "Not Ready" status is cleared, thus not passing emissions. Owners with pre-2015 models have slightly better luck, but in all cases, the codes eventually reappear. Do not buy a catless thinking a spacer will help. 200 Cell cats will also fail even with spacers. The ONLY cat that will not throw codes is a factory cat.

MY FRIEND SAID I CAN PLUG IN A SPECIAL ADAPTER TO FAKE THE SIGNAL: Doesn't work. Those work on narrowband systems. The Fiat has a wideband O2 and it isn't fooled by devices that send a fake O2 sensor signal.

MY FRIEND SAID I CAN USE A "MINI-CAT": Doesn't work. It may delay the P0420 signal, unfortunately, it will replace that with other error codes related to cat warmup time and temperature.

SO THERE IS NO WAY: That's about it.

Don't go catless or high flow cat if passing emissions matters to you.

Delete

What’s different about pre 2015 cars?

retrophit wrote: ↑Sat Jun 20, 2020 2:08 pm What’s different about pre 2015 cars?

The upper O2 sensor location was changed in 2015, and apparently, along with that the profile in the PCM became more sensitive. They tend to throw the P0420 code a lot more quickly than the earlier years.

I have a 2013 Sport with a header and high flow cat. I got the cel . I tried a spacer and it didn't help at all. We don't even have state inspections in my state ,so I don't worry about emissions test. The car runs great, but I would like to be rid of the light. I'll get with my tuner on it.

sportfan wrote: ↑Sat Jun 20, 2020 8:46 pm I have a 2013 Sport with a header and high flow cat. I got the cel . I tried a spacer and it didn't help at all. We don't even have state inspections in my state ,so I don't worry about emissions test. The car runs great, but I would like to be rid of the light. I'll get with my tuner on it.

Someone on Faceballs told me I was wrong about not having to pass emissions in some parts of Texas. Where I live there is no emissions. If you're in one of the metro areas (Houston, DFW, etc) then you do have to be tested.

Now this is something I haven’t seen before. I’ve seen simple spacers, but never a spacer with its own little cat (kitten?)! Humm...

https://www.fabspeed.com/universal-o2-s ... er-single/

I tried a mini-cat in 2015 with catless MPX downpipe. If I remember correctly it delayed the inevitable but didn't really work.

retrophit wrote: ↑Sun Jun 21, 2020 9:26 am Now this is something I haven’t seen before. I’ve seen simple spacers, but never a spacer with its own little cat (kitten?)! Humm...

https://www.fabspeed.com/universal-o2-s ... er-single/

I did the mini cat also with a 200 cell. It indeed stopped the P0420. However it replaced it with two other codes related to the O2 sensor not warming up quickly enough and not reading properly. Basically the PCM could still tell something was not according to spec and thus still didn't set the "Ready" status or turn off the light.

On top of that, with relatively few miles, the tiny bit of cat material in the spacer was burning out pretty quickly.

You guys sure know how to ruin a fella’s day! Lol. Thanks for saving me from myself.