I have mentioned this in someone else's post a few weeks ago. It's really to ask whether someone else has come across this bizarre problem.

At the beginning of this summer, when it was beginning to get hot, I went out one morning and couldn't open the car (F10 523i 2011) with the fob. I got in using the manual key, but the vehicle was as dead as a doornail. I assumed that, somehow, the battery had drained. I attempted to jump start the car, without any success. Reaching into the glove box to get the Green Flag information, I saw that the glove box light was on, therefore, there must have been some power. I then tried to start it, and it fired up.

The next day I was left stranded at the gym because it wouldn't start again! Although the car suggested placing the key fob next to the steering column, that didn't work. NB I'd left the car in the sun, it's being a particularly hot day. I went home, picked up the spare key, and started it by placing that one next to the steering column. I took it straight round to a local garage, but, apart from disconnectiing the driver's door 'comfort access ' function and replacing both key fob batteries, the mechanic wasn't able to help. 

It happened two or three times after that, always on a hot day, and the car's being in the sun. I took it to my local independent who couldn't replicate the problem, but, after having read the fault codes, they did take out the comfort access on all four doors, and, again replaced the key fob batteries. Since then, the problem has occurred two or three times, always in hot weather with the car exposed to the sun. At least, the vehicle has started with the key being held against the steering column so I haven't been stranded. Now that cooler weather has returned, the problem seems to have gone away. 

Would I be right in thinking that the problem lies with the diversity antenna, the heat beating down on the roof causing it to malfunction in some way? It might be worth mentioning that the car is an import from Singapore, and has had the instrument cluster changed so that it reads in miles not kilometres. I've had the vehicle since October last year and have been completely trouble free until this summer's hot weather.

Many thanks for any insights into this conundrum!

 

Phil

 

  

Morning Philip

That's a weird one after all Singapore isn't exactly known for its cool climate !! It may well be worth checking the diversity antenna there were some well documented issues with 5 series back in the early 2000's but the issue there was water ingress. Worth checking though, the instrument cluster change I wouldn't think would have and effect on the door locking system BMW store mileage covered in two places so if you have a tamper dot beside the recorded miles it wasn't registered correctly to your chassis. If there is no tamper dot it was done properly 

Dave

 

Thank you Dave for your reply. There have been issues with other F10s, F11s and E60s with similar problems, i.e. the fobs not talking to the car, but this has either been due to a blown fuse, or a faulty antenna, the problem remaining until one of the latter has been replaced. The problems with mine have been intermittent.

I have heard that if the steering wheel cowling has been removed, e.g. to change the instrument cluster, this could cause difficulties with the fobs, but ten months without problems would seem to rule that out. The mileage seems to be correct and converted accurately from kilometres to miles. The water ingress would have concerned the E60 which did have a few issues, which one would have hoped had been ironed out with the F10.

The issue doesn't seem to be completely restricted to BMW - my partner said she'd parked her Ford Focus (also keyless entry) in a supermarket car park, and couldn't start it when she returned. 

For the rest of the summer, I'll try to park in the shade!

Phil

Morning Philip

I have seen a PCB board from a car imported from Japan that had warped and cracked due to heat. on a cool day everything operating as normal Hot day parked in the sun and no Instruments showing in the cluster, no warning lights speedo rev counter nothing. Apparently it foxed a couple of specialists before it was found.

Possibly something similar in your diversity antenna?

Dave

Hi Dave

Apologies for not having acknowledged your reply earlier. I think you could well be right regarding the warping of a PCB board - I'm assuming with reference to the diversity antenna. My suspicion is that under a baking hot roof, something somewhere expands and short circuits something else, hence the lack of communication with the key fobs.

Antennae are expensive to buy (almost £400) and a pig to remove and fit, hence not worth it yet! Everything with the car is now running very smoothly, and I'm thinking of having the comfort access reconnected - at least until next summer!

Phil