datgay - from what you've said you don't have the same problem at all. After not using your car for 5 days I'm not surprised the sensors didnt work - and believe that is by design. After so many hours of inactivity (maybe 24/48?) the sensors switch off to save battery - I'm sure it tells you this in the manual.

I guess for energy saving sake proximity sensors are switched off after two or three days. I think then you should at least pull door handle. ;)

Advanced key
 

New here but found this thread.
I have a 2007 A5 3.0Tdi with the same problem.
It was like this when bought the car (Private sale).
It has never worked for me although the car will open remotely
It also recognises the key inside so you can start with START/STOP button.
I presume all these work the same way whether it's a3 a4 a5 etc.

Got codes read and got these.
03286 Sensor for contact with door handle front right short with ground.
03285 Sensor for contact with door handle front left short with ground.
03287 Sensors for contact with door handles open circuit/short with power

Same problem without the luxory of warranty
 

Is this a recall deal by any chance. I recently bought an 09 with 50k+ on it and I noticed this feature doesn't function. Anyone know what this runs if one pays out of pocket? I can't imagine it's worth the money.

I swapped both sensor on doors and all is good £74 each

Would you happen to remember the part number for those sensors?
I have to replace mine.

Got the s4 B8 model and have the exact same problem. If you have those part numbers - I'll grab them too ;)

I just ordered two of these. Part number 4G8 927 753
Outside Door Handle Bar Sensor Pin Switch 4G8927753 for Audi A4 A5 A6 A7 A8 Q5 | eBay

My car, Audi A4 B8

I know this is a really old thread, but when I did my searching on Google, this was one of the primary ones that came up. I read through this thread, and didn't see what I have found to be a solution for the Op's problem.

I had exact same issues, and long story made short, my battery was low.

The computer in these vehicles, will shut down systems to conserve battery power when the battery gets below a certain point. That way you don't have a dead battery just to keep the advanced smart key system active.

All I did was charge my battery overnight, and the problem went away. I may need to get a new battery, but I take lots of short driving trips, so I think my battery just died because it was not being given a chance to charge. I also live in a cold climate, and use my seat heaters and another electric's, so that puts additional drain on the electrical system.

Again, sorry for the old resurrection. But I thought I would post what I found as a solution for me.

Resurrecting this thread. Recently picked up an old A4 (B8) in great condition. Have never been able to get keyless entry to work. After reading up on it, I see it could be the battery, could be the sensor(s), or simply could be that the feature is not supported, but I believe it should be. I don't know how to confirm if the car has the prestige trim, but based on the features it has, I believe it does. Any help would be appreciated. Wouldn't bother with a dealer fix, but possibly a DIY if it's not very difficult.. Thanks.