For those of you that don't wanna spend on software, I found this page with a trick on how to take care of the check engine light. Is from the Mazda forums but should work the same. Sorry if it's a re-post.

http://www.msprotege.com/forum/showthread.php?t=123634664

For those of you that don't wanna spend on software, I found this page with a trick on how to take care of the check engine light. Is from the Mazda forums but should work the same. Sorry if it's a re-post.

http://www.msprotege.com/forum/showthread.php?t=123634664

Man, if you have spent the time and $$ on doing the headers, you might as well get the Software. It is worth every penny!!! I went with the D/A Race and it is a different car now!

I know, I haven't done headers yet. BTW I am doing the s/w too, this is just for some of the guys here that don't get the s/w.

haha I rember when they first came up with that, (I am/was a member of mazda forums) I have seen it and it does actually work. this is the spark plug non-foulers trick right? I diddnt bother to click on the link....I am way to busy for that.

hahaha, yeah it is. lol

nice find

sorry bro...doesnt work on our cars...

its been tried by some people with headers. the point behind this is to remove the sensors from direct exhaust flow, they end up picking up a different signal that looks like there are cats.

unfortunately, our sensors are sitting in the headers and the exhaust flow is super hot and still burning and has no direction yet so it goes right up to the sensors.

Now it was thought that possibly using two of these plug defoulers could work but unfortunately there is no room for that.

there are only two ways to beat the SES light for no cats... get software.

use the o2 simulator i created once i decide its ok to be sold for actual money. Right now I only know it works on my car so i am sure it will work for 2001-2002 models. I have yet to find someone with an 03+ that needs one and will try it out although as long as the sensor is the same it should theoretically work. I just dont know how the DME reads the signal in the newer models and if it has any testing system. they are all narrow band sensors so i dont see why it wouldnt work.

Also, I want to make sure it will last. I have had it on my car for a few months now and it is working great, I just finished my registration as well with no problems.


(Note:this item is for off-road use only and I do not use it on my own personal vehicle unless I am on a track where EPA requirements state I do not need a catalyst in the exhaust system. The emissions system of my vehicle runs properly in the condition it came from the factory in, while I am driving on any public roads):devillook

I have yet to find someone with an 03+ that needs one and will try it out although as long as the sensor is the same it should theoretically work.

I think I can help you out with that. :)

heh, well locally. So I can build it, install it, and then if need be.. remove it. It does require cutting your o2 sensor wires to splice in. not that they cant be reconnected. both front and rear o2 sensors can be cut and reconnected with no adverse effects.

but unless you want to pay for one, It will be difficult for me to do. and I would feel like crap if it didnt work and we would then have to eat shipping costs.

however, if you are ever in the atlanta area... shoot me a PM and I can actually unplug my setup and plug it directly into yours and we will have an answer in about 10 minutes.

the post cat sensors are in the headders on an e46? as far as I know the non-fouler trick is only for the post-cat sensors(the second 02 sensors down stream, after all the cats) there are 2 sets of cats on the e46 right? "pre cats" on the headers and regular placement down stream from that. maybe the first set of o2 sensors moniter the functionality of the pre-cats as well as the mixture? I dont see how, but I am easly confused heh.

these secondary sensors measure the o2 levels after the cats have done their thing, and it should be measuring a constant voltage, if the were no cats the o2 readings would be erratic. all a simulator is is a resistor that gives the same voltage signal as if the cats were working normaly and trick the 02 sensors into reading a nice "clean" 02 signal.
why they are so expencive for bmw's and are like $15 for every other obd2 car, I have no Idea, but I suppose you could make your own with a trip to radio shack, (just don't tell AA)

I dont have any experience messing with any of this, sims or non-foulers on bmws. My car is completly cat less and I have no cel...mainly because I threw the o2 sensors away and removed the cel bulb from the cluster haha. but it would also be on for about 3 other reasons anyway.

yes all the o2 sensors are in the headers. the pre cats are right next to the head, then the cats are in the headers, then the post cat o2's are located still in the headers.

unfortunately a simple resistor to correct voltage will not work on our cars and actually does not work on many cars, not just BMW. In fact in the realm of o2 sensor readings, BMW does not make it very hard compared to a few others. and I think its actually harder in the e36 M3.

anyway, there is a pulsing circuit that sends the voltage to the DME and imitates a stoich 14.7 AFR while the car is in closed loop operation. Once the car goes into open loop it no longer reads the o2 sensor signal. The other issue is that most other people dont simulate the o2 sensor heater circuit if their sensor has one.

Our o2 sensors, while they are all narrow band (not wide band), have the signal circuit, but all they have a heater circuit. the o2 sensor heater does just what it says, heats up the sensor so that carbon residue does not build up on the sensor at start up and during operation. The DME however can read resistance over the heater circuit and will still throw an "o2 heater circuit" SES code and you will have a check engine light.

This was my problem for the longest time. I was actually able to simulate the signal circuit early on. the pulsing circuit was successfull and left me only with an "o2 heater circuit" signal code which i had to simulate.

Here is the problem... most cars use a higher resistance heater circuit which doesnt get as hot. they all run on a 14V circuit from the car so the higher the resistance the cooler the resistor provided the wattage rating is enough. with a higher resistance the wattage capability of the resistor can be lower. BMW decided to use a nice low resistance and the circuit changes resistance as the sensor heats up.

basically the sensor starts out with a 2.4 ohm resistance when cold. in a 14V system that can make the circuit very hot (which is the point), but if it stayed like that the circuit would burn out. So as the heat increases, the resistance increases and at operating temperature the circuit is at the proper resistance for the voltage of the car and the wattage rating of the circuit.. so it stops getting hotter.

the heater circuit goes from 2.4ohms to 4.8 ohms and on a 14V system if you do the math you will need a 40Watt resistor to keep it from burning out completely. And even with that wattage, it will still get really hot. The problem is that no one on the planet earth makes a 4.8ohm resistor or a 2.4 in a 40 watt rating. and the 2.4 would have to have twice the wattage rating to keep from burning out instantly... so it would have to be 80watts.

the problem is that the DME will start reading the resistance at a certain point and if the value does not come out to what it expects, it will throw a code. So we had to buy resistors after resistors to find the combination that worked best and stayed coolest.

Right now I have it installed in my car and there are no check engine lights whatsoever. But I need to make sure this thing lasts more than a few months. the problem is that I can only garauntee the simulator for as long as i have used it on my car which is a few months.

i would love to start selling it, but i just cant bring myself to take people's money if I cant be absolutely sure. there are a few people who want it anyway and they know the risk that it might not work if they have on 03 or newer or they want it for their 330.

maybe i will sell them anyway.. even then i will feel bad if they dont work for someone... i dont know..
(for off road use only, etc.)

awsome, sounds like you did your home work!

I guess the non-fouler trick only works on proteges, (they also have heated senors btw).
I have never heard of the heaters reading o2, but I have never looked into the sensors that closely at all. maybe thats why 02 sensors for my car are $190 a piece at the dealer ship, $90 a piece at autozone, and 4 wire bosch o2 sensors for other (mostly usdm) vehicles are dirt cheap

you should find a couple people on the forums to just let them try them out and do some real world testing, then if yours and they'ers last say 4 months with no problems, you would have a pretty good bet that they all will last longer.

I feel that solid state electronics are pretty durable, there's nothing to wear out, just as long as things arnt melting, smoking, & shorting, in theory if they last 2 seconds they should last years.

just if you do sell them make them inexpencive. I am sick of simple electronic components costing hundreds of dollars, ok, yea it may have taken the companey a while to figure out the numbers and stuff but when you pay $500 for a plastic box with a couple 25 cent resistors inside its kind of discuraging. (I am exadurating a little)
then people like you come along and figure it out on your own and then there is hope for a realistic price.... or at least lower. The under ground revolution is now! lol, but seriously make them! or at least tell people how to make them, its for the good of the poor bimmer comunity.