This morning I could not unlock the C7 by pressing/jiggling the door sensor pad. Using the unlock feature on the key fob, the door unlocked. After that, the door sensor pad began working. However after being parked for a few hours the pad stopped working again. I don't know if this is cold temperature related (I'm in South Florida), or if the pad needs to be cleaned.
There was a thread on how to clean the pad posted a few years ago, I believe on the C6 forum, but I couldn't locate it. Can anyone provide info on how to get at, and clean the pad?

 

Try the passenger door as well when the driver door does not respond.

I bet it won't open either.

My guess is you have a weak FOB battery.

 

FOB battery

 

I agree check FOB battery first. Then check door switches. Turn off the motion sensor, roll down the window and close the door and let it lock. Reach in and see if the inside door button will release the door. If it doesn't and the door pad doesn't unless you use the FOB to unlock the car there could be something wrong in the door control module. There is a process to finding out what is wrong. First check FOB, second check both doors for proper operation. If both doors fail then it is some sort of electrical problem that is common to both doors. If one door doesn't operate properly while the other does then you know the problem is in that door. Then check to make sure both the inside and outside switches work. If they both fail then it is an electrical problem to both switches which means the door control module. While doing that keep track of what is happening with the window indexing. When door control modules go bad the windows can start doing screwy things as well. If one of the switches works and the other doesn't then the problem is in the switch that doesn't work, this is usually the outside door pad. You can check that by swapping door pads from one door to the other. If it is the pad the failure will move with the pad. You can clean the pad or replace it. The pads are cheap and they are covered under the 3 year/36K mile warranty. If the car is under warranty I would let the dealer worry about the problem.

Bill