Comfort access stopped working

[Spandex]

This is more for for others information really, as I’ve fixed the problem:

A few weeks ago my comfort access stopped working completely - wouldn’t unlock from any handle and wouldn’t start without the key in the slot. Unlocked using the fob button fine though. There were no faults logged and no messages on the screen. When I pressed the start button it would just flash up the ‘key not present’ icon. I changed the fob battery (although I’d have expected low battery messages if this was the issue) but it didn’t help.

Reading around various forums, I saw a few people posting to say that this can be caused by a dying main battery. Prior to the comfort access failing I had occasionally had the increased battery discharge message come up, so I was leaning towards this being the problem. Checking the existing battery, I saw it was a BMW branded one with a 2007 manufacture date so it was 10 years old and almost certainly the original factory item.

Anyway, I changed the battery and sure enough, comfort access is working again. I have no idea why a failing battery causes this one strange symptom. Some people have speculated that the car disables the CA to reduce load on the battery (presumably having the antennas powered all the time draws a lot of power). Kind of makes sense, although you’d think the car would let you know it was doing it.

Hopefully this will help anyone with a similar problem.

[graemeX5]

Hi

Thanks for the post and the solution on comfort access as the cars get older it's more likely we are going to get these probs and it's nice to know it can be solved by the battery.

These cars seem to be heavily dependent on the battery being in a good state otherwise it can cause probs.

Graeme

[Spandex]

Well, it might not be the end of it, unfortunately. This morning my car wouldn't unlock or start without using the fob. When I got into work, I switched the engine off, took the key out the slot, then restarted the engine successfully without putting the key back in. Then, while the engine was running it popped up the 'no key detected' message again.

So, it seems that I've gone from CA not working at all to CA working intermittently.

[X5Sport]

Has the battery change been coded into the car?

[Spandex]

Yes, I registered the new battery.

[X5Sport]

It could be a bad new battery in the fob.  Not unknown if it has been stored for a while.

[Spandex]

Worth a try I guess. I have a fresh pack somewhere so I'll give it a go over the weekend.

[Nine468]

Not too sure if this might help,,,
But i do seem to remember reading somewhere on here that if you have excessive battery drain, and the car has comfort access/soft close it could be down to a faulty door handle...
It might be worth a quick search...

[Spandex]

I do have faulty sensors on the front passenger door handle. Probably a broken wire, but I’ve not bothered investigating it much. That was like that long before the current CA fault though. I haven’t had the battery drain warning for a while now though.

Incidentally, putting another new battery in the fob over the weekend didn’t help. Most of the time CA still doesn’t work. If I drive for a while, then stop the car and take the key out the slot I can almost always restart the engine without putting the key back in the slot. Sometimes it will put up the ‘key not detected’ message shortly after though. Sometimes it doesn’t.

All a bit weird. Will probably just live with it for a while, while I look for a specialist near me. I’m more interested in getting my thermostat fixed at the moment - 16mpg is no fun. :blink: