Header CEL

[2BIT]

I was just wondering if anyone had ever figured out how NOT to get a CEL when headers are installed. I know this was kicked around alot on the old site and just wanted to know if anyone had come up with something on this other than unplug the light

[sed]

you need to get an o2 sensor simulator so the ecu thinks that the air is getting "cleaned" by the cats.

shawn :)

[OdessitPashka]

Well, i know some people never got CEL and others just decided to deal with it! in some section there is a thread about o2 simulator, i think someone is trying to use it, maybe that will help!

[watson80]

or relocate ur 02 sensor

[Steve]

A header with the first o2 sensor and then a high-flow cat and then the second o2 sensor should do the job. You need both o2 sensors or a simulator instead of the second. You just have to make sure that the high-flow cat has a high enough cell count.

[XDGT03]

no one who has a complete header-back system avoided a cel. there is a sim www.o2simulator.com/ (here) that i will be trying. Hopefully I will order it today.

Fordfasterer tried a sim but couldn't get it to work porperly.

The other option which i have ranted about about a 100 times is this:

measure the distance from the core of the oem cat to the center point of the o2 sensor on the stock set up. I think it is about 14.5 inches. When you put in the new system, make sure the distance from the new cat and the repositioned o2 sensor is exactly the same. this "should" prevent the cel. I haven't tried it and no one else has yet either. I just lazy and kinda like looking at the little orange engine on my dash. :rolleyes:

[evil247]

I do not get CELS. Full header and Cat Back exhaust. 2nd O2 sensor relocated to behind 2nd cat. First o2 in the header. Alex(Geraldelroy) does not have a cel anymore either. I lengthened his o2 sensor as well. I used cat5 cable wiring when creating the extensions, it is know to be very good wiring. Maybe this is why some people who have tried to extend the sensor have gotten a CEL, cheap wiring.

[slvrsleeper]

I have have been getting CELs about every two or three weeks with my system. I have ghetto o2 sim (resistors soldered into the wiring) The code that usually comes up is slow response from 2nd sensor.

[Steve]

evil, you used two cats after the header?

[Bnystrom]

measure the distance from the core of the oem cat to the center point of the o2 sensor on the stock set up. I think it is about 14.5 inches. When you put in the new system, make sure the distance from the new cat and the repositioned o2 sensor is exactly the same. this "should" prevent the cel. I

Why would the distance matter? Shouldn't the exhaust gas composition be the same regardless of the distance from the cat? I can't imagine that the gas temp would be an issue, either.

[GTSpeedRacer]

Evil- what make/model of cat do you use?

[O_GT]

or relocate ur 02 sensorthats what I did and no cel

[2BIT]

What ever happened to the good old days of just taking off the manifold and bolting on a header with out all the BS.
I wanna get the OBX off ebay, but I just dont want to go through all this hassle with rewiring 02 sensors and CEL's. Are all the new cars like this now, or is Hyundai just the lucky one??

[evil247]

evil, you used two cats after the header?

No just the stock 2nd cat in its original location.


Evil- what make/model of cat do you use?
See above answer

[2BIT]

I was wondering if all those guys that did that group buy from HP.com awhile back for those SS Autochrome headers liked tham, or if they were CEL 'd to death.

[OdessitPashka]

I still have CEL after relocating my o2 sensor... but it goes away for 200 mi after reseting ECU.

[XDGT03]

Why would the distance matter?

I talked with an exhaust guy who went to some training where they said moving the o2 sensor as little as 1/4 inch can cause a cel.

Shouldn't the exhaust gas composition be the same regardless of the distance from the cat?

Maybe as the gas cools, it changes in compsotion. (just talking out my *** on this one)

I can't imagine that the gas temp would be an issue, either.

Ours are heated. However, too close to the cat may cause it to "overheat" and give false readings because of it, or the above statement.

evil, how far is you o2 from your cat?

O_GT, what kinda wiring did you use and how far away is the o2 from the cat and did you use the oem second cat or aftermarket?

[O_GT]

I spliced and soldered the the harness side and used bigger gauge wire as not to cause more resistance.Do NOT SPLICE the sensor side this will damage it.Make the wires as short a possible this will keep resistance down.I used my OEM cat and as far as the distance Ill measure it at work to see what it is

[XDGT03]

I'm thinking the oem cat must have something to do with not getting a cel.

I used some automotive wiring that was large gauge by a bit. It is wire that the mechanic shop buys in bulk. Not the most expensive, but not cheap *** stuff either. I spliced on the harness side. My sensor is about 8 inches from the aftermarket cat.

[evil247]

I spliced and soldered the the harness side and used bigger gauge wire as not to cause more resistance.Do NOT SPLICE the sensor side this will damage it. I am a little confused by this maybe I am just reading it wrong. By sensor side are you referring to the actual o2 sensor that you can disconnect. When disconnected it is about 7-8 inches in length? If so that is what I cut, extended and soldered, on 3 cars now with no problems whatsoever. Maybe if you can post a pic or schematic from HMA.

evil, how far is you o2 from your cat? I'll try and check today

[2BIT]

I want to do a header on the car, but I am concerned about the CEL thing. I dont want to go through the BS with it. If I buy a header and take the car to a shop like Meinike or Midas to get the header installed are they gonna know WTF they are doing so I don't get a CEL? Doesn't sound promising so far.

[evil247]

highly doubt that meinike or any other place would be willing to extend your o2 sensor for you. It isn't very hard. I have rudimentart sautering skills at best and have done 4 so far with no problems.

[gerardoleroy]

I'm a bit late on this but yeah evil fix my o2 sensor and now I don't have a cel anymore.

[2BIT]

I guess I should rephrase the question. I want to do a header, but I don't want to have CEL hassles. Here in Nevada every year you have to have a smog check to register your car. If you have a CEL, you automatically FAIL .

I just want a muffler shop to install a header, and me not get a CEL so I don't have this smog check issue. Enlightenment??? :confused:

[2GTS]

To not have a cel you need to extend the O2 sensor wires and relocate the sensor after the remaining cat or use a O2 sensor sim. Either of these options will work but a Meineke or Merlins probably won't be willing to do any electrical work.

[2BIT]

Isnt there a header out there that will just bolt up to the stock system so you don't get the CEL??

[2GTS]

The closest thing to bolt up with no mod would be the EvoFusion or Hotshot header but you will still need to lengthen and relocate the 2nd O2 sensor to be behind the cat. I think the Hotshot header might even include a kit to relocate the sensor but I'm not positive.

[Black04XD2]

The closest thing to bolt up with no mod would be the EvoFusion or Hotshot header but you will still need to lengthen and relocate the 2nd O2 sensor to be behind the cat. I think the Hotshot header might even include a kit to relocate the sensor but I'm not positive.

It does.

[2BIT]

Great, 500 bucks for a Hotshot Header. After hearing that, and the quote below from Jay, it was a nice idea, but thats all it will be.

Basically if having a cel and emmisions testing is a concern you have very little you can do. Evil seems to be the only one who has managed to get no cel. He has done this by retaining the stock second cat and relocating the second O2 sensor behind it. This does not guarantee everyone will be as successfull as him. Plus retaining the second cat theoretically eliminates the gains provided by the header (I still am not convinced of any real gains with a header anyhow).
So if I was to run a header I would use one like the EvoFusion that eliminates both cats and have the cel. When it is time to test for emmisions I would bolt the stock manifold and cat back in with the O2 sensors and then remove them the day after the test. A PITA but really the only real option if you want to achieve the full potential a header might be able to provide on our cars.
The last thing to consider is that a header provides grounds for the dealer to void the 10year 100,000 mile powertrain warranty your car came with. The grounds being the incorrect O2 sensor readings that can effect the proper fuel mixture that the car was designed for. Plus there are the legal matters associated with using a part sold for off road use only.
In my mind there is too many negatives to warrant a header on the Elantra. So far they have not been proven to provide any hp gains and most actually loose torque. Until a Dynojet dyno with a header that shows at least 5hp and 5 ft/lb gains are seen my feelings will remain the same. Save your money for gasoline instead.

[evil247]

Great, 500 bucks for a Hotshot Header. After hearing that, and the quote below from Jay, it was a nice idea, but thats all it will be. Evil seems to be the only one who has managed to get no cel. He has done this by retaining the stock second cat and relocating the second O2 sensor behind it

Not true. Alex(geraldelroy) does not have a CEL either. I was the one who extended the o2 sensor for him though. Maybe the ones who tried to extend their o2 sensors did not use quality wire or sauter the connections who knows. But of the 4 cars that I have done none have had a CEL because of the second o2 sensor. Also the gain was very noticeable when the header was installed. Ask mike about the 1st time he drove Ang's car after I installed the header. It made him go out and buy one. I am not saying that the header gives 15-20hp but I also don't feel that you would be able to feel a 1-2 hp increase. If you notice all the cars that are in the 15s all have a header. Just my .02 and for a 100-150 bucks and a little bit of work I feel it is definately worth it. Now if I had paid 400-500 I would probably be a little disappointed.

[2BIT]

Evil, guess you got the 02 sensor touch... :cool:

[Jameson]

I have a CEL after putting on my header. The code is P0133, HO2S Circuit Slow Responsive (Bank 1, Sensor 1). How do I fix it? Any insight Evil?

[evil247]

damn you should have let me look at it today at the meet. I was the one with the Black hatchback. I don't know the codes but can you explain how the o2 sensors are setup?

[Jameson]

damn you should have let me look at it today at the meet. I was the one with the Black hatchback. I don't know the codes but can you explain how the o2 sensors are setup?

Sorry man, I didn't really think to ask you today at the meet. From my understanding from what Hyundai webtech says about that code, it is the first o2 sensor that is the problem. The guy at autozone told me that that code means the sensor is dirty. I asked if there was a way to clean it and he told me there is but I would probably have to clean it weekly and I should just buy a new sensor instead. So I dunno, how would I clean it? Id' rather try that first than drop cash on a new sensor...

[evil247]

I wonder if you are throwing the same cel as angel. Hyundai said it was her first o2 sensor as well. She will be moving the bung further down in the header to try and rememdy the problem. I wonder if the hyundai tech would try the older sensor moved down to see if it would correct it without replacing it. I will talk to her and find out if it is possible. If so and it corrects the problem it may help you out as well. I find it weird that I have never had a problem with my first sensor seeing as how the location is the same.

[Jameson]

I wonder if you are throwing the same cel as angel. Hyundai said it was her first o2 sensor as well. She will be moving the bung further down in the header to try and rememdy the problem. I wonder if the hyundai tech would try the older sensor moved down to see if it would correct it without replacing it. I will talk to her and find out if it is possible. If so and it corrects the problem it may help you out as well. I find it weird that I have never had a problem with my first sensor seeing as how the location is the same.

I don't really know. My only guess would be the brand and octane of gas you use might make a difference. Some burn more cleanly than others. I guess if the gas you use doesn't burn very cleanly, it dirties up the o2 sensor faster. I'll probably just buy a new sensor. Someone suggested trying to get it replaced under warranty but that will never happen. As soon as they see the header, they will say that's whats causing it.

I looked into prices on O2 sensors and now I'm very sad. To get a replacement from Hyundai that will probably develop the same problem very quickly, roughly $100. And for a Bosch O2 sensor from Advance Auto Parts....$349!! :mad: So, anyone know how to clean one of these things? :confused:

[OdessitPashka]

just go to the junk yard and take a sensor off of elantra!!!

[Jameson]

just go to the junk yard and take a sensor off of elantra!!!

Well it would have to be a 02 or newer. I already did my research and it turns out that the PN for the 02 Elantra is the same as the PN for the 03 Tib. But thanks. I didn't really think of the junk yard, although I may not have any luck anyway. Last time I went to the local junk yard, there was not a single late model hyundai.

[Onelove5683]

evil, with this evofusion setup it bolt directly to the catback. there are two bungs already for the o2 but theres not cat... it will suck to have to weld a cat in there or is this my only chance against cel?

[Bnystrom]

evil, with this evofusion setup it bolt directly to the catback. there are two bungs already for the o2 but theres not cat... it will suck to have to weld a cat in there or is this my only chance against cel?

If you don't have any cat's, you will get a CEL. The other option beside adding a cat is to use an O2 sensor similator, such as those from www.o2simulator.com.

[evil247]

evil, with this evofusion setup it bolt directly to the catback. there are two bungs already for the o2 but theres not cat... it will suck to have to weld a cat in there or is this my only chance against cel?

Do you have a CEL now? I have also wondered how much change does the 2nd o2 sensor have to detect to think there is a cat there. I mean if you could have the first o2 sensor high up and then extend the 2nd o2 sensor way back in the exhaust stream would the exhaust gasses have changed enough by then to make it seem like the exhaust had passed through a cat? To answer your ? though I don't think anyone has a header and no cel with out at least having one cat.

[only1esco]

Wow, this is always a hot topic, I love it. :)

[Jameson]

Well, I gave in and bought a new o2 sensor from my Hyundai dealer today, so no more CELs for me! ;)

[04 elantra cvvt]

The problem with the 02 sims is that it fools the computer into thinking the car is at wide open throttle at all times. So, you get too much fuel. Re-location is a better option.

[2GTS]

The 2nd O2 sensor isn't the sensor telling the ecu the car is running WOT. The tps and the 1st O2 sensor are responsible for those duties. The 2nd sensor is just looking for cleaner air than what the 1st sensor read to make sure the cats are working.

[slvrsleeper]

Here we go again LOL ! I have the Evo Fusion system from head to tailpipe and I have struggled with various and sundry issues with it ever since. My car 2001 GLS with 67000 miles on it has thrown the CEL three times once was slow response from the second O2 sensor second was the EGR (unrelated to the header) and I don't know what the third one was my guy didn't tell me. My second O2 sensor has been lengthened per Evil 247's model and the car runs STRONG The major issue I have had was NVH! but that is another story which has been told many times before.

[04 elantra cvvt]

I am not saying that the second o2 is telling the comp that you are at WOT, but the sim gives the readings of WOT at all times. The sim cannot varry it's readings, so they set them to read max flow at all times. It is great for drag racing, but not very streetable. From what I can gather, lengthening the o2 is the best option.

[2GTS]

You aren't using a 02 Sim for the 1st sensor and that is the sensor that measures the A/F mixture and has the ecu make adjustments. The second sensor has nothing to do with wot or anything other than making sure the air got cleaned between sensor 1 and sensor 2.

[XDGT03]

yes, and the "cleaned" exhaust has to be within a certain range (o2 molecules per million) or it will cause a cel. Using the oem second cat seems to be the only way to avoid a cel with a header. Universal cats, high flo cats don't seem to get the job done.

[slvrsleeper]

IMHO the aftermarket cats DO work they just have to be allowed to "burn in" My sytem has been trouble free (no CEL) for about a month and a half now. Thats with 65 miles of daily commuting five days a week though. When everything was new on the car I had all my problems occur, also remember that the stock ECU in the XD is a "block-learn" computer which requires a certain number of ignition cycles to learn a new mod, and if you pile a bunch of mods together like I did you are asking for CEL trouble.

[only1esco]

You just need to re-position your O2 sensor

[XDGT03]

You just need to re-position your O2 sensor

Who me? I moved it back about 6" when i did my crazy side exhaust. Still cell.

IMHO the aftermarket cats DO work they just have to be allowed to "burn in" My sytem has been trouble free (no CEL) for about a month and a half now.

I have had my catco cat for almost 14K. I went nearly 2k before I got a cel. Now i get one after about 300miles after a OBDII reset.

My cat is working within acceptable levels at idle, but as soon as it starts having to burn down the gases the signal varies too much and I get the cel.

[Jameson]

Damn, my CEL is back. Anyone got any ideas? It's the front o2 sensor. The code says ho2s circuit slow response bank 1 sensor 1. Someone suggested the problem may be too much backpressure is causing the sensor to malfuction and a high-flow cat may solve the problem. I've also been told to buy a Bosch performance o2 sensor, but I've also been told I'll have the same problem even with the Bosch sensor... :(