Hello I have a 2010 A5 Cabriolet which has recently developed a fault with the central locking.

When I use the remote key fob, it definitely connects with the car as the lights flash and I can hear a clunk. However, the drivers door does not unlock, and the passenger door sometimes unlocks and sometimes doesn't.

This started a couple of weeks ago so I wonder if it could be related to the cold weather and maybe my battery is struggling. Also, I only use the car for very short runs so I suspect the battery doesn't get much of a chance to charge.

Does my suspicion that it may be the battery sound likely, or is there another likely fault to be investigated first?

Thank you.

Debbie

It's definitely worth considering the battery especially if it's old as a failing battery can cause all sorts of electrical issues. If it's not the battery then I'd recommend a diagnostic check to see if any fault codes flag up 

It could indeed be down to an ailing battery aggravated by the cold weather.

How old is the battery Debbie? 
Cold weather also adversely affects the cables in the flexible harness twixt the front hinge pillar ( A post) and the front edge of the door frame. Cables are prone to fracture as they become less flexible, so my first - free- port of call would be to check there. 
If all is well there, then I would take the car for a good 25 mile run, then call into a Halfords store and get the battery and alternator efficiencies checked there.

If the battery is found to be below par, then please come back to us before committing to buy - in the best interest of your bank card. 
If all is well with the battery, then suspect a faulty door lock, but please come back to us anyway.

Regards,

Gareth. 
 

The battery must be at least 8 years old. I will go out for a run to see if that solves the problem. Then follow the other steps that you have recommended if that doesn't work.

Thank you.

Debbie

Thanks Debbie,

An 8 year old battery needs replacing, even if it isn’t the sole culprit. 
Now knowing that, I wouldn’t bother getting it checked. If it were mine, I would simply invest in a good quality new replacement. 
In case it helps, it would be well worth putting your registration number into Tayna Batteries and Parts in Motion’s websites, and consider their Exide brand ( which I now prefer over Varta or Bosch). Both these suppliers also operate on EBay where you generally get free delivery. 
The new battery will need coding to the car, so you will need to set this up with a trusted local independent,  before swopping them over.

Please let us know how you get on Debbie.

Happy New Year to you and yours.

Regards,

Gareth. 

 

19 hours ago, A5Debbie said:

This started a couple of weeks ago so I wonder if it could be related to the cold weather and maybe my battery is struggling. Also, I only use the car for very short runs so I suspect the battery doesn't get much of a chance to charge.

Winter weather always reveals the weakness of a dying battery. At eight years old it undoubtedly needs to be renewed. Don't forget to get it coded to the car.

Did you make any progress with this Debbie?

Thanks everyone for your help. Put the existing battery on charge overnight but still nothing, so have taken your advice and bought a new battery. That seems to have sorted it, thanks.

Have you had the battery coded to the car? 

Yes, I checked with the guy in the car battery shop who replaced the battery and he said he did it. Thanks