mdmiller50

My family and I decided to spend the July 4 weekend in Palm Springs. Drove our 2021 A5 SB. The car has a little over 36,000 miles on the clock. During our eight-mile drive from the hotel to dinner at 6:00 it was 119 degrees (F) outside (the high that day was a record-setting 124). Maybe a mile into the trip, the proximity sensors seemed to become extremely sensitive. This affected all four corners of the car. They would alarm every time a car was even in the next lane, or at a stop light. Very annoying. I chalked it up to the heat since it's never happened before but was wondering if anyone else had experienced anything similar.

m444

I have noticed this too on very hot & very dry days.

I am guessing, it is most likely it is due to the dry air, absorbing less of the radar signal (~77GHz): https://www.sciencedirect.com/scienc...24271622003367

also: https://www.itu.int/dms_pub/itu-r/op...2014-PDF-E.pdf

SSR = short range radar

"SRR signals will propagate much further in an environment with an atmospheric attenuation of 0.15 dB/km than, say, one where the attenuation is 6 dB/km. Such a diminution in atmospheric attenuation in principle affords the compensating ability to turn down the radar power while maintaining its effectiveness"

ChicagoNB

I've been complaining about this for the last two years. The last time I was in for service (just a couple of weeks ago) the service tech said there's a TSA bulletin about how atmospheric conditions make the sensors go off at random. I haven't looked it up yet.

SMac770

Just to be clear, specifically which sensors are you talking about? There's radars for ACC in the front bumper, there's radars for the rear side assist (lane change assist) on sides of the rear bumper, there's ultrasonic sensors in the front and rear bumpers but I'm not sure they would be active at any normal driving speed, and more on the wheel wells specifically for park steer assist. Lots of nanny "the sky is falling" bs in these cars; which specific warning/alarm is in question?

The TSB https://static.nhtsa.gov/odi/tsbs/20...48208-0001.pdf is in reference to the ultrasonic sensors.
This TSB is not in reference to the B9 vehicles, but it's a curious thing: https://static.nhtsa.gov/odi/tsbs/20...07131-0001.pdf
If you are talking about the ultrasonics, could be simply heat deformation of the surrounding panel or other cause of misalignment creating bounce back.

mdmiller50

Hi! I've been an Audi convert for less than a year, so I can't say exactly which of the many sensors were acting crazy. My guess is it was those in the bumpers, front and rear, because they were all chirping at me during normal driving down Highway 111. After the sun went down, it had cooled off a little (114 degrees F from 124) and we were on our way back to our condo everything was back to normal.

Nikon1

Are those “Actual” versus “Feels Like” temperatures? That is some brutally hot climate either way!

— John

mdmiller50

Actual temperatures. Palm Springs, CA set an all-time record of 124 Friday, July 5 when we were there to celebrate the 4th. Here's one of the news articles to confirm;
124 in Palm Springs? Historic heat wave toppling all-time temperature records in the West (foxla.com)

mdmiller50

You did some research sir! Quite interesting stuff.