W210 Outside air temperature sender
 

The outside air temp gauge on my 99 E300 has gone haywire. With outside temperature in the mid to high 90s my display on the dashboard reads something balmy (or barmy?) in the mid 70s. Where is the sender for that feature? I'm told it's somewhere behind the front bumper but that covers a lot of real estate. How can I find and is there a way to test it to see if it is the problem? Thanks!

mine is clipped on the front bumper tow hook cover. Mine was cracked,I dried area with acetone,then super glued with the gel. Been working 5 years now.

On my facelifted W210 it was next to the left foglamp (or maybe right - forgot and I dont have the car), its the tiny nub sticking out of the faux mesh grill surrounding the lamp. That nub always would snag my wash mitt. :D

its not that difficult to change either.

To test use an ohms meter on sensor after it is unplugged. Generally low ohms = hot and high = cold. You will need some sort of temp to resistance chart.

If you disconnect the sensor, the temp will likely swing to -40 F or some other really low number. If you short the wires together the temp will go high.

Yep, drivers side foglight, bottom slot in grill hard against end of slot.

Found it--I think
 

Found it in the grill below the bumper close to the driver side fog light--see picture attached. Now how to I get access to it? Does the grill come off? Access from under the car? Thanks!

jack up the car and remove the plastic liner underneath it, On later W210 it had trap doors in it to service the fog lamps themselves, That sensor was reachable if you had child sized hands.

removing the bottom splash panel is easier.

Thanks! I'll try the little flap first. If that doesn't work then I'll try removing the splash panel. Since I don't expect to be able to see much via the flap, do you know how the sensor/sender is attached to the grill and how the connecting wire is attached?

The flap / tow hook covers tend to break the clips when removed and won't go back on.

I can speak of my W210 - it was attached to the grill by two prongs - and it had a wiring connector, basic bosch type 2 pin which you pinch to remove.

On my W124 it was a metal job which was screwed on the bumper with no terminating end nearby - it was one wire all the way to the fuse box and ended in the mercedes banana plug 2 pin connector.

I've seen some cars come in where the customer used a curb to remove the front, lower cover:eek:.

Oh, yes thats the easiest way for most people. - They also try to realign the radiator carrier with that technique.