The beeping is intermittent therefore it is not going to show everytime. Having been in this line so long, it is not surprising when such situation occurs.
Get the dealer to replace the sensor or disable it and test if problem goes away.
GMC Acadia battery problem is similar to your case and seems there are no sure fix for the problem.
I will get some of my fellow technicians on this and hope someone has some information that might help.
If the A/C and radio/sat nav starts working when ignition is turned, the problem should be the control module losing its memory, similar to when battery is disconnected.
Tuesday, November 2nd, 2010 AT 9:32 AM