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Discussion Starter #1 (Edited)
So today I cleaned my AUC sensor, if you are not certain what this part is, it controls the automatic re-circulation function of your HVAC, you know, that little A with a circle. When the system detects pollutants or bad quality air, the vents close up so it doesnt enter the cabin.

I googled and searched these forums, I noticed that there wasnt a diy to clean it out and replace the air filter inside the sensor, so I thought I would post my own. If your sensor has never been cleaned before, i am sure its filthy in similar or worse condition than mine. I figured you fanatics might enjoy yet another diy project, and this is a super simple one.

Step 1. AUC sensor sits on top of your fan shroud (on so equiped e46's). Detach harness plug, and remove sensor. to remove it, you will slide it to the left then slowly pry it upwards and back forwards. This will disengage the clips.





Step 2. Use a flathead and pull on the flap, the filter portion will slide out.



Observe dirty, disintegrating air element from 12yrs of road use.





Step 3. Use compressed air to lightly remove dust out of inner portion of sensor. This is what sniffs the air quality.



Step4. I found the air filter to be identical in weave and density to this filter I use for my fishtanks. Cut out a small portion and insert into the sliding box.





Step5. Slide the tray back into the housing, and reinstall. To install it, tillt and put the right hand side clips first, then pull to the left and push down. The clips on the side away from the connector can bend, the side next to the connector cannot, so keep this in mind and reinstall is a breeze. dont force it or you will break your shroud.

Now enjoy another 10yrs of service before you clean it again! :D
 

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awesome! thanx
 

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nice DIY! i'm going to do this now.
 

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Awesome. I just got the auc short circuit to ground error, seems it has triggered 9 times in the past. My sensor in the box is positioned differently, yours look like it is perpendicular to the filter, mine is parallel. However not sure if cleaning it will resolve the error, but def worth a shot. Thanks.
 

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good info that one! in my scanner 1.4 that sensor appear in red and i was going to buy a new one but now that i know hot to clean it i hope i works better thanks!
 

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Alright i open my sensor it was empty inside i went to a local home-deport and i bought some filter similar to OEM but my sensor is still in red on the scanner! What to do know?
 

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AWESOME! I have always wondered how in the hell the auto-circulation function knows when the air is dirty/smelly. Would be great to get confirmation of the actual filter material.
 

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thanks for the info. gonna do this soon :thumbup:
 

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I saw this sensor in the schematics, but had no idea where it was. Good info! I would never have attempted to open that box, without knowing what was inside. I have learned that lesson the hard way... :)

Edit: I just noticed the OP has not been on here for almost a year. He may not even have an e46 at this point.
 

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Interesting thread, but, I question the need to replace the filter. The sensor is a Figaro TGS 822 which is for sensing Organic Solvent Vapors. Here is the data sheet
http://www.figarosensor.com/products/822pdf.pdf
This sensor is used to detect chemicals like Acetone, Ethanol, Benzene, n-Hexane, Isobutane and carbon monoxide. A similar detector is used to detect carbon monoxide in home CO detectors (I have some Figaro sensors for detecting CO). The sensors in home CO detectors are only rated for 5 years of use. If you are getting AUC sensor errors in the IHKA module like 28 AUC Sensor-open circuit or 30 AUC Heating-short circuit to ground, I would suggest changing the sensor rather than just changing the filter, which, I don't believe will do anything. The original part number is 64.11-8 391 470 and has been replaced by 64.11-6 917 001. ECS Tuning has the part for $46.84 (as of 4/9/2013)
 
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