High pitched steady beep

[Yota2007]

My husband's 2005 PT Cruiser has a steady high pitched noise that sounds like the beep from the Emergency Messaging System, just not as loud. Oddly, it continues to beep when the car is off. It happened the first time this morning: he got in, started the car, beep started. Turned off car, beep continued. Turned back on, beep continued.
Any suggestions on what this could be?

[garner49]

Disconnect the negative terminal on the battery for about a minute - that will reset everything (yes the radio station presets too). If after re-connecting it's still there - have the computer read for fault codes.

Also: has someone put a tracker device on the car????

[Yota2007]

Thanks! We'll give it a try.

As for the tracker device, we're not interesting enough to track.

[quicksilverdon]

Did he buy the car new? If not, prior owner may have put in something - like an alarm system...