97 540i: Can't Find External Temperature Sensor

[P11]

Hey guys, I've been plagued with the -40 degrees displaying on my dash... after searching the forums I found a DIY to fix the problem but I just can't seem to locate my sensor. I checked under both fog lights directly under the bumper (both passenger and drive) and all I see is plastic covering the undercarriage. Any help would be appreciated.

[PJB]

Check that plastic that you see covering the undercarriage. The sensor is not mounted to the bumper but to a portion of the front passenger's wheel well:

#14 in the diagram, but on the passenger's side:
Click the picture to go to an online parts database


Here's a picture:

[jamesdc4]

Check that plastic that you see covering the undercarriage. The sensor is not mounted to the bumper but to a portion of the front passenger's wheel well:

#14 in the diagram, but on the passenger's side:
Click the picture to go to an online parts database


Here's a picture:

Absolutely true!
Where is the External Temperature Sensor located?

[srb6537]

Make sure you're looking at the right part of the undercarriage. it should be on the passenger side. I had cracked the plastic that the sensor was mounted to. it eventually fell off, leaving just the two sensor wires. that's when I got the -40 reading. Bottom line, your sensor might be gone...

[Qsilver7]

Dollars to donuts...if the OP looked on the passenger side and couldn't see anything...I bet the whole she-bang is gone!

"She's missin' Cap'tin...she's bin ripped right off to the gullet!"

For instance...some interesting pics from past threads on this topic (found by minutes using the ADVANCED SEARCH feature...narrowing the search words to the e39 forum only)

• Dangling temp sensor due to entire under-panel being gone: http://forums.bimmerforums.com/forum...16&postcount=1
• Another "entirely missing temp sensor got -40 on dash" thread: http://forums.bimmerforums.com/forum...ng+temp+sensor

[P11]

I found the wire tucked in under the front bumper. It turns out the entire under panel is gone. Does anyone have the part numbers for the under panel and temp sensor?

Thanks

[PJB]

I found the wire tucked in under the front bumper. It turns out the entire under panel is gone. Does anyone have the part numbers for the under panel and temp sensor?

Thanks

See the following line in my first post (post #2):
"Click the picture to go to an online parts database"

There you'll find the part number for the lower engine compartment cover in an online parts database, already preset for a 1997 540i.

See the links Qsilver7 posted (post #5):
There you'll find the part number for the external temperature sensor for a 540i.

[P11]

Thanks for the info, since I only have wires hanging would I need more than just the sensor and under panel?

[PJB]

Thanks for the info, since I only have wires hanging would I need more than just the sensor and under panel?

That depends on what is at the end of the wires. If the ends are in tact then just the sensor is needed. If the ends are frayed, cut, or otherwise damaged, then I would suggest that in addition to the sensor, you pick up Bavarian Autosport's External Air Temperature Sensor Plug Repair Kit (part number 61138365340KIT):



You can buy the passenger's lower engine compartment cover, the external temperature sensor, and the wiring repair kit for about $122 USD before shipping.

[P11]

The ends of the wires appear to have been cut. What does my post count have to be in order to post pictures?

[jamesdc4]

Thanks for the info, since I only have wires hanging would I need more than just the sensor and under panel?

You will need the wiring harness (part #3 below).
http://www.realoem.com/bmw/showparts...79&hg=65&fg=70


Qsilver7 has posted in the past about a kit you can purchase that has everything you need.

Edit: PJB posted it above while I was typing.

[P11]

The shipping would cost me $17 alone since I live in Toronto. I'll most likely go to my local dealership and buy the necessary parts. Thanks for the help.

[jamesdc4]

The ends of the wires appear to have been cut. What does my post count have to be in order to post pictures?

You need 15 posts to gain photo posting privileges.
How many posts do I need before I can....?

[P11]

Thank you sir.

[Jamesfogarty05]

I'm having this same problem with a friends car. The entire sensor was ripped off and just the 2 wires are dangling, I tried connecting the wires directly to the sensor both ways and it still reads -40 if I touch the 2 wires together I get +120 do I need to get the entire wiring harness? or am I just missing a step like disconnecting the battery or something? Also the interior fan and A/C are not working at all. I have full control of the center cluster, everything lights up but nothings coming out are these problems related. I've checked all the fuses in the trunk and in the glove compartment and they all appear to be fine

[jamesdc4]

I'm having this same problem with a friends car. The entire sensor was ripped off and just the 2 wires are dangling, I tried connecting the wires directly to the sensor both ways and it still reads -40 if I touch the 2 wires together I get +120 do I need to get the entire wiring harness? or am I just missing a step like disconnecting the battery or something? Also the interior fan and A/C are not working at all. I have full control of the center cluster, everything lights up but nothings coming out are these problems related. I've checked all the fuses in the trunk and in the glove compartment and they all appear to be fine

I believe you need the wiring harness kit and yes, the problems are related.

[Jamesfogarty05]

I believe you need the wiring harness kit and yes, the problems are related.

Thank you very much sir