The outside (ambient) air temp gauge on my 99 E300TD (W210) is malfunctioning. Example: On some recent torrid east coast days where the temperatures hovered in the high 90s the gauge inside the car read a balmy low 70s outside. It's usually off by 20 or so degrees below the real outdoor temp. I want to start by checking or replacing the sensor. But where the heck is it on the W210? Is there a simple way to test it to rule out a problem at the dashboard end? I hear it may be somewhere behind or the front bumper but there's quite a bit of real estate down there. How can I get to it? I appreciate any help!