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Old 09-23-2011, 01:59 PM   #1
VECTOR
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Question Ambient air temperature sensor malfunction?

I got a check engine light on so I went down to my local Autozone and it printed out that my ambient air temperature sensor was either due to open or short circuit condition. They reset the code for me, and the next thing I know my A/C was not working for 5 minutes or so, then came back on.

So can this thing affect my A/C performance, and where is it located?

Ever since my bumper became dislodged the A/C has acted up intermittently, so I am guess the sensor is somewhere in the front bumper/spoiler?

Autozone said they do not sell the part/s, so how expensive of a fix is this?
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Old 09-23-2011, 02:45 PM   #2
E46-Cabrio
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AUC sensor.

http://blog.bavauto.com/wp-content/u.../11/fig711.jpg
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Old 09-23-2011, 06:15 PM   #3
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Quote:
Originally Posted by E46-Cabrio View Post
Thanks for the picture of where it is located. Hopefully others will be along to answer some of the questions I posed.
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Old 09-24-2011, 02:52 AM   #4
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Errr, that's not a picture of where it's located

Your ambient temperature sensor is located in a recess under your front bumper on the driver's side if you live in the USA. Scrape it or dislodge it and it will play havoc with your A/C functioning. Usually it will effect real crazy readings when you selection outside air temperature on the stalk computer.
I think the sensor is about 80, just guessing, and those who know say there is a bracket you will probably need too.
Replacement cures what ails you. I have never had this problem.
Let us know how you make out.


Quote:
Originally Posted by VECTOR View Post
I got a check engine light on so I went down to my local Autozone and it printed out that my ambient air temperature sensor was either due to open or short circuit condition. They reset the code for me, and the next thing I know my A/C was not working for 5 minutes or so, then came back on.

So can this thing affect my A/C performance, and where is it located?

Ever since my bumper became dislodged the A/C has acted up intermittently, so I am guess the sensor is somewhere in the front bumper/spoiler?

Autozone said they do not sell the part/s, so how expensive of a fix is this?
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Old 09-27-2011, 04:42 PM   #5
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Quote:
Originally Posted by Stinger9 View Post
Your ambient temperature sensor is located in a recess under your front bumper on the driver's side if you live in the USA. Scrape it or dislodge it and it will play havoc with your A/C functioning. Usually it will effect real crazy readings when you selection outside air temperature on the stalk computer.
I think the sensor is about 80, just guessing, and those who know say there is a bracket you will probably need too.
Replacement cures what ails you. I have never had this problem.
Let us know how you make out.
The drivers side splash guard in front became dislodged due to the mishap I had with the bumper(in another recent thread). When it came off, a long piece of wire along with the AAT sensor came with it. I suspect I could splice it back into the existing wiring if I could find it as a temporary fix.

As you said it is playing havoc with my A/C giving me reading ranging from -40 to +122. Of course when it reads +122 the A/C is nice and cold, but at -40 it does not work at all. I just wish there was a schematic or diagram on how the wiring is laid out to make it easier for me to find the wires it came dislodged from.
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Old 09-27-2011, 05:14 PM   #6
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Here is the outside temperature sensor schematic.
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Old 09-27-2011, 10:18 PM   #7
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Finding the wiring

The schematic posted here does confirm that you only have two wires to worry about, but no routing is detailed. If only you could get to another BMW to trace the wires back to where yours ripped free. Have you already removed the plastic undershield to explore? I suspect you'll get nowhere before you do this.
Search this and perhaps other boards as this has been discussed over and over. I do not remember if there is a socket involved.


Quote:
Originally Posted by VECTOR View Post
The drivers side splash guard in front became dislodged due to the mishap I had with the bumper(in another recent thread). When it came off, a long piece of wire along with the AAT sensor came with it. I suspect I could splice it back into the existing wiring if I could find it as a temporary fix.

As you said it is playing havoc with my A/C giving me reading ranging from -40 to +122. Of course when it reads +122 the A/C is nice and cold, but at -40 it does not work at all. I just wish there was a schematic or diagram on how the wiring is laid out to make it easier for me to find the wires it came dislodged from.
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Old 09-28-2011, 12:46 AM   #8
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Quote:
Originally Posted by Stinger9 View Post
The schematic posted here does confirm that you only have two wires to worry about, but no routing is detailed. If only you could get to another BMW to trace the wires back to where yours ripped free. Have you already removed the plastic undershield to explore? I suspect you'll get nowhere before you do this.
Search this and perhaps other boards as this has been discussed over and over. I do not remember if there is a socket involved.
What is interesting about the schematic (thanks E46-Cabrio) is it looks like what is called the sensor is a module under the hood, not the part in the front bumper. For lack of a better way of putting it, could the part down there be a probe vs. the sensor itself?

If you look at the picture earlier in the thread;

http://blog.bavauto.com/wp-content/u.../11/fig711.jpg

it looks much different than the piece I am referring to which looks like these;

http://www.google.com/#q=e46+Ambient...w=1280&bih=607

Does my question make sense?

I just found these pictures which might be helpful;

http://www.digitalunderpants.com/obc...tempsensor.jpg

http://www.digitalunderpants.com/obc...empsensor2.jpg

Last edited by VECTOR; 09-28-2011 at 12:51 AM.
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Old 09-28-2011, 05:43 AM   #9
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A quick search here for "Ambient Temp Sensor" returns this great thread-

http://forum.e46fanatics.com/showthr...nt+temp+sensor

Page 5 has a great set of pictures.......includes info on the wires and the connector part number (if it is missing too)
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Old 09-28-2011, 11:19 AM   #10
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The thing about this that I find truly amazing is that the temp sensor in the brake duct talks to the OD II Diagnostic System at all. I've never heard of a connection between this sensor and the Check Engine (SERVICE ENGINE SOON) light.

I agree completely that the discussion is on the correct sensor -- you crashed the car, the sensor has been problematic ever since -- because the sensor certainly does live in a location that would be exposed to a minor collision. The problem I have is that there is a relationship between the sensor and the Check Engine light. I'd be interested in the specific code that came back...
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Old 04-10-2012, 10:17 PM   #11
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[QUOTE=jdstrickland;13628294]The thing about this that I find truly amazing is that the temp sensor in the brake duct talks to the OD II Diagnostic System at all. I've never heard of a connection between this sensor and the Check Engine (SERVICE ENGINE SOON) light.

Today I had the same problem loosing my lower part of my fender where this sensor is located and the SERVICE ENGINE SOON light came out.
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Old 04-11-2012, 10:26 AM   #12
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[QUOTE=BigMexicanWinner;14279930]
Quote:
Originally Posted by jdstrickland View Post
The thing about this that I find truly amazing is that the temp sensor in the brake duct talks to the OD II Diagnostic System at all. I've never heard of a connection between this sensor and the Check Engine (SERVICE ENGINE SOON) light.

Today I had the same problem loosing my lower part of my fender where this sensor is located and the SERVICE ENGINE SOON light came out.
I still have not gotten mine fixed(long story involving insurance), but one funny thing is that during normal days it operates fine. The service engine light is still on, but as long as it does not rain, the A/C blows cold. But when it rains, I'm assuming the exposed wires get moist, the temperature reading starts bouncing around on the dash and the A/C stops cooling.
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Old 08-31-2012, 07:07 PM   #13
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Question

Ok guys, a new mystery.

The body shop took off the old bumper and found exposed wires, BUT on the passenger side of the front end, not the left. Also the wires are a different color than the end of the sensor probe I still have.
Needless to say this is strange because the place for the end of the sensor probe to fit into is on the drivers side, not the passenger side.

So the body shop is speculating that there might be some other electronic item that was ripped off on the passenger side as well.

Any ideas what that wire might have tied into?
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Old 08-31-2012, 10:22 PM   #14
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There are two sensors, one in each fender liner.

The driver's side is the longer "pencil" shaped ambient temperature sensor that feeds the temp display (and apparently also interacts with the automatic climate control).

The passenger side fender liner may have a "hockey puck" shaped thermal switch for heated windshield washer jets, if so equipped. The wires are there even if the car doesn't have the thermal switch installed.
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Old 08-31-2012, 10:40 PM   #15
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if the ambient\air temperature sensor is bad, wouldn't the OBD show the ambient temperature to be like -40 degrees or something?
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Old 08-31-2012, 11:07 PM   #16
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Quote:
Originally Posted by Cobra View Post
if the ambient\air temperature sensor is bad, wouldn't the OBD show the ambient temperature to be like -40 degrees or something?
yes and beeps too.

The sensor itself never goes bad, most likely the wires are ripped.
Reconnect them yourself same basic electronic skills
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Old 09-01-2012, 12:01 AM   #17
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Originally Posted by MercForHire View Post

Reconnect them yourself same basic electronic skills
Crimping or soldering wires is electrical skills, not electronic.
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Old 09-01-2012, 12:04 AM   #18
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Quote:
Originally Posted by richkopena View Post

The passenger side fender liner may have a "hockey puck" shaped thermal switch for heated windshield washer jets, if so equipped. The wires are there even if the car doesn't have the thermal switch installed.
Universal wiring harness. Very informative.
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Old 09-01-2012, 12:34 AM   #19
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Quote:
Originally Posted by Stinger9 View Post
Crimping or soldering wires is electrical skills, not electronic.
thanks my english was a bit off.
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Old 09-01-2012, 02:17 AM   #20
VECTOR
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Cool

Quote:
Originally Posted by richkopena View Post
There are two sensors, one in each fender liner.

The driver's side is the longer "pencil" shaped ambient temperature sensor that feeds the temp display (and apparently also interacts with the automatic climate control).

The passenger side fender liner may have a "hockey puck" shaped thermal switch for heated windshield washer jets, if so equipped. The wires are there even if the car doesn't have the thermal switch installed.
Great info.

Now is there any way to determine if I had the hockey puck style sensor by vin, model number, etc.? Any attachments to the washer tank that might give it away?
One clue might be that the new splash guard for the passenger side has the hole area, but it must be punched out. Where as my old one had the opening there, so one can assume that since the hole was punched out, it was there. Keep in mind that if that is all it does(washer fluid), then living in S Florida it will not be needed.
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