[scottjoh]

thanks, that was the fault code i have....i ll fix it tomorrow.

Fix it (replace the $50 sensor) only if you want the automatic air recycle feature. Most people don't understand this feature and don't care. When set to Auto Recirculate the HVAC system will stay in fresh air mode and if the sensor detects large amounts of exhaust fumes in a tunnel for example (you can look up the sensor to find out what gases it is used to detect) it will automatically switch to recirculate. With a bad sensor it won't automatically switch and you'll have to switch manually. The response time of the sensor detecting a cloud of black exhaust from a diesel truck will be too late and you are better off switching manual when you see the cloud.

If your goal is to have zero faults when you scan all the modules in your car then good luck. That is a loosing battle. The mechanics hate it when customers scan their own car and come in complaining about code that comes up after a repair that are totally unrelated. Codes will happen. Don't treat everyone as a problem that needs to be taken care off.

 

[jacksilver]

fixed it, you were totally right.the filter was like sand inside so i bought the similar filter put inside cleared it...perfect....thank you so much...great DIY

 

[Alex323Ci]

If you're good at soldering, you can get one of those for $11 shipped http://www.aliexpress.com/item/FIGA...O-TGS-822-Gas-Sensor-for-the-detection-of-Organic-Solvent-Vapors/656495742.html

Hmm has anyone tried to solder this replacement sensor piece in? anyone confirm it will work?

 

[Zpzp96]

Thank you so much!

Maybe I should clean mine soon


Sent from BimmerApp mobile app

 

[scottjoh]

The normal faults that occur when the AUC sensor goes bad are not fixed by replacing the stupid filter. If you have fault codes for the AUC sensor then the sensor needs to be replaced.

 

[werdstrave]

I just found this sensor under my plastic belly pan as I was unscrewing it and snooping around. It obviously fell off and has been there for a long time. I'm not getting any errors on my dash, I'm just wondering how critical of a part this was. I opened it up to as shown and mine has no batting stuff in it. Just dead air. How critical is this part?

 

[werdstrave]

I seem to have been doing fine without it

 

[bee-em-dougle-u]

Kewl! You learn sumthin' new every day. I thought that box was a relay for the fan motor.

 

[markusmarkus]

It sits above and behind the radiator???? How in the hell does it get fresh air???


Sent from BimmerApp mobile app

 

[Benny Minn]

It sits above and behind the radiator???? How in the hell does it get fresh air???


Sent from BimmerApp mobile app

Perhaps the large fan sitting next to it solves that problem.

 

[emeni09]

Hi all, I have been using the info from this forum for a long time and today I think I can give a little back.
i bought my e46 in november and since they I always found small (or not so small things to fix on it). I had bad experiences with mechanics and I don't really trust them. and when I notice that I know more than them when it comes to diagnosis and troubleshoot, I get really pissed, especially when they charge an arm and a leg. so most of the times I try to fix as much as I can by myself.
anyhow, a few weeks ago I had some problems with the engine. it was running rich and I had some misfires. I borrowed a carsoft interface from a friend and tried to find the culprit. either the lambda sensors or some vacuum/pressure leaks. Thankfully, when i was about to install a pressure gauge on the oil dipstick to see what happens I found the huge hole where the oil cap used to be :facepalm:
yeah, sometimes I'm stupid. after replacing the cap (took me one week to notice it) I started reading all the modules and found the AUC faulty.
Now what was the this AUC and why was it either shorted or open circuit? hmmm. took me a while on google and found this topic. after seeing the datasheet, I also have the same opinion as Alex. Such a simple analog circuit can't be restored by just a cleaning and once it goes bad, it goes bad.
I wanted to change it but it wasn't a high priority, especially since BMW want huge bucks for such a small and simple thing and also because my dealer has outrageous prices, even at the independent BMW specialist who have extremely good prices this AUC seemed as an expensive thing.

I decided that since I have most of the tools needed for soldering, and that in the worst case scenario, where I would destroy the plastic case, I could 3D print myself a new case to give it a try at replacing the sensor only. I'm pretty good at soldering and I have all the tools you could imagine for soldering at work.


Anyhow, ordered the sensor from ebay (I barelly trust paypal with my credit card, and I don't want my bank account drained just for 1buck).
I bought the sensor from a seller in Taiwan for 12 USD including registered shipping. The sensor came pretty fast a few days ago.
Today I was waiting for some replays on my emails and noticed the sensor on my desk. I decided it was time to change it.
Bare with me, as this is my first tutorial. I realized I should take pictures a little too late, didn't took enough and sometimes forgot to take them at all. Sorry for that, but at least I hope what I did helps. Also sorry for the size of the pictures, I tried uploading them tot he forum, but for some reason the "open" window doesn't come to the front and my browser freezes.

Anyhow everybody know already where the sensor is and how to open the case (if you don't see the first post).
As Alex said, I also though the sensor is soldered initially, but when I opened the case, I realized that there are two tabs holding it in place.
if you look at the picture below you can actually see them circled with red.

Easy fix, took a pair of pliers and a screw driver to push the tabs back and started pooling... not working... tried pooling harder.... not working. At this point the sensor case was pretty scratched and the sensor didn't moved.
No problem, I have a nipper (hope that's the correct term, you an actually see a smaller one in the above pciture). Placed the case tight in there... and tried pulling even harder... at this point I realized that the sensor won't come out (maybe it's soldered?) and that the sensor case was already loose.

ok.... now what?

looked in the case and at the connector and notice that the sensor is not melded into the plastic AUC case.... good, it should come out.

looked around and managed to find the tabs which where holding the sensor down. in the picture below you can see the sensor holder and in the next one only the case. There are four tabs. two on each side which need to be pushed back (circled with red). They have to be pushed pretty hard, but be careful not to break any. I manage to break one. I'm not responsible if you break them.
YOU HAVE BEEN WARNED. how I did it (at least for 3 of them), was to pull the tabs out with a small screw driver and the put something under the tab to keep it out of the hole.

Use your imagination, just remember that there are three of them. I then tried to pull again with the pliers from the figaro case.... nothing. Then I decided that it would be also possible to push through the connector, in-between the pins of the connector. It worked, although you need to put some pressure.
AGAIN, IF YOU BREAK IT, IT AIN'T MY FAULT.

This is how it looks when it comes out.

GOOD, now this piece of :censor: looks molded in plastic... so it it's soldered I will have to brake the plastic. Tried with a heat gun to melt it... In the end, I realized that I can abuse it. So I decided to start destroying the Figaro. took some pliers and some cutting pliers and started breaking it apart. nifty little thing. Broke almost all of it. As it thought it would be soldered I decided to cut each pin and to start pulling on them individually. this way, if it is solder I can still have a chance to fix it.
good, after breaking out all the plastic of the sensor I was left with only the pins. took the pliers started pulling them one at a time and they came out without any problem. Individually it was possible to remove them, but together, NO.
here is the sensor socket

Now I placed the new sensor in the socket (you can see below the 6 holes). it was a very tight fit. i'm 100% sure that even without the tabs holding it down, I couldn't have removed it without breaking it into pieces.
it would be smart to learn from my mistakes: REMEMBER HOW THE ORIGINAL SENSOR WAS PLACED SO YOU CAN PUT THE NEW ONE CORRECTLY, THE PINS ARE SYMMETRICAL. I had to come to the forum and see how is the correct position. I will verify this next week when my VAGCOM will arrive.

Anyhow. I pushed the sensor holder back into the case.
one extra thing to look out for are the auto socket pins. you might bend them when removing or pushing back the sensor and then you will have troubles putting it back on the car. It took me a good 10 minutes to bend them back. one of them was 0.1 mm out of alignment. If this happens to you. the best thing is to pus the plug hard into the AUC, then remove it, and the pins will leave a mark on the plug. This way you know where the pin are actually touching and which way to bend them back. Now I have to go to the pet store to replace the filter.


hope this was helpful.

As a piece of advice, if I were to do it again. I would try to destroy the sensor in the case, without trying to pull the holder out. It should be possible, and less time consuming (it took forever to lift the tabs without breaking them).
Only in the case where I would not be able to fully remove them, would I try again to full the holder out. Take you time. break the orange plastic brutally and make sure to clear the debris afterwards. there are also some holes at the bottom of the case for ventilation.
The pins, after you break the plastic mold will look like some nails (with a mushroom head) try pulling them one at a time. after all of them are out. push the new sensor in. make sure to remember how it was placed as it will be nearly impossible to pull it out in one piece and completely stupid.
if you do forget (like me :facepalm: ) try looking at the first picture in this topic to see the correct position.

P.S. the pictures in high-resolution (maybe someone needs them) are available here (the first registration free photo sharing site) : http://iceimg.com/90jm

 

[Alex323Ci]

^ nice work and information :bow:

 

[scottjoh]

Nice write up, but, why?
Why spend the time and money to replace it? The problem has no noticeable symptoms unless you knew what that little A on the recirculate button meant, it was on and you smelled something you know shouldn't have. 99% of the people who have this feature in their car probably never read the owners manual or if they did don't remember what it does.
I bet if you didn't see the fault code in the IHKA module log you would have never in a million years known that it was bad or even cared. If you drive with your windows open, or with the windows closed with it set to fresh air or recirculate without the A then the sensor is useless or not used anyway.

 

[SoCalZman]

Nice write up, but, why?
Why spend the time and money to replace it? The problem has no noticeable symptoms unless you knew what that little A on the recirculate button meant, it was on and you smelled something you know shouldn't have. 99% of the people who have this feature in their car probably never read the owners manual or if they did don't remember what it does.
I bet if you didn't see the fault code in the IHKA module log you would have never in a million years known that it was bad or even cared. If you drive with your windows open, or with the windows closed with it set to fresh air or recirculate without the A then the sensor is useless or not used anyway.

Hah. I wonder how much time and money bmw spent developing this feature.


Sent from BimmerApp mobile app

 

[emeni09]

well, to be honest, I noticed that it wasn't working pretty early... I either have a soon dying CAT or a leak in the exhaust, but after a long run (I tend to be aggressive) when I stop for 2-3 minutes I can smell the fumes in my car. Also, living in the most socialist country in the world (russia and china only dream to be like this) taxes for cars are outrageous, so people tend to drive old cars whom are most of the time not up to code (most of them buy them and the next MOT scrape them). I don't even want to mention how much I payed for my e46, since most people who don't know the tax system here think I'm mad/retarded or that I got scammed.
Anyhow, I looked everywhere for the "E46 automatic re-circulation" and couldn't find anything.
This was only the first reason, the second one is the most important: I love cars, I always wanted my own car and worked very hard to buy one, I got stuck with a BMW (didn't really understood what's so special about them before having one) and I kind of ignored/didn't knew about some of its problems. For me, fixing small or big things in a car is a pleasure and a way to relax, I plan to keep the car for at least 3 years and while it is mine, I will do my best for everything to work as it should or better .
I love this little metal thing who gives me tones of joy, sings to me on a cold morning when I rev it up and from time to time jokes about killing me when I push it a little too far

P.S. I spent only 12 USD on this, and the time, I either had to fantasize about having my car prewired for alarm (I have to make a harness soon) or doing this.

 

[Benny Minn]

Well done, emeni09! I will have to try this soon.

 

[Alex323Ci]

bought the Figaro TGS 822 and went to replace mine today. hey guess what they aren't all the same
i should have checked before but didn't even think they had different AUC modules. the one on my M3 is a different part, and thus has a differnt sensor much smaller.


so look at yours before you buy. also if anyone in SoCal wants a Brand new Figaro sensor for $10 picked up lemme know.

 

[deepblue7]

Hello,

When I diagnose my car with DIS I see 'IHKA AUC Sensor Open Circuit' error as below.

Is the reason dirty filter or should I replace the part when I see open circuit error.

 

[scottjoh]

You have to replace the sensor. Replacing the batting will do absolutely nothing!

 

[emeni09]

One quick tip for everybody who wants to know if it's only a dirty filter or the sensor is dead.
After I changed the sensor, I didn't had a filter to replace the one I had. This was dark, almost burned. As soon as I started the AC, with the Automatic re-circulation, the module detected pollution and switched to recirculating. The easiest way to detect this is to put the fan on maximum and to cycle (wait 5 seconds between cycles) on the modes. you will clearly hear the difference between re-circulation and outside air. If the car automatic features goes to re-circulation you have a dirty filter, if it goes to outside air, the filter is good or the sensor is dead.
If you have an error, most probably you have a dead sensor.
If I were to do it again, i wouldn't try to take the entire case apart. with some pliers, I would try to destroy the old sensor in the case and then place the new one in its place. You will still have to destroy the old sensor, as it was impossible for me to take it out in one piece. It isn't soldered, but the tight fit and the 6 legs make a very good mechanical lock.