High-pitched noise in your Mazda CX-9?

Last year, I purchased a Mazda CX-9, and have been very happy with the vehicle--with one notable exception. There were times when I started the car and immediately noticed a high-pitched sound going off periodically, almost like a dog whistle or hearing test beep. It was intermittent, really annoying, and I couldn't tell where it was coming from.

Finally one day, I figured it out. The car comes with Bluetooth capabilities. I realized that I only heard the sound when I didn't have my cell phone turned on, or when I had the bluetooth feature on the phone disabled. It seems the high-pitched sound is the car searching for a bluetooth connection. Once it finds one (e.g. if my cell phone IS on and has bluetooth engaged) then the sound goes away. If I don't have my phone with me or it's shut off, the sound persists.

One fix that I've found for stopping the sound without having keep the phone on is to turn on the radio and tune it to AUX mode. No more beep.

It never occurred to me to blog about this until today, when I was approached by another CX-9 owner who told me that he'd been back to his Mazda dealership six times trying to figure out this annoying problem. Whoops! If you're having a similar problem with your CX-9, give the "Aux" trick a try and let me know if it works for you.