Coded keys and mobile phones

  Diemmess 16:27 16 Jul 05
Locked

For some time I've heard tales of non-starting cars, when their owners parked in a public car park close to a phone mast.

Today in the Telegraph (page 23) an article by Rachel Simon mentions being rescued by AA and asked if she had allowed her car keys to be close to her mobile...? Tut Tut.

I can't link any phone company to any car by name, and a brief Google-time gave me click here

Car security systems and key code methods are changing all the time. Obviously some are affected, some not.

Can anyone fill in some detail with names of safer manufacturers or systems which avoid the problem?

  spuds 18:27 16 Jul 05

This is a problem that seems to be increasing, and various debates on the subject still bring conflicting evidence. The police are using the Airwave system, which is beginning to cause some concern, especially if used in close [long-term]proximity to human beings.

A Times article click here

  wiz-king 21:08 16 Jul 05

Get a car that uses real keys, fit a hidden cut out button if you must and use the brain power that you have been provided with to remember to lock the car.

But back to your question, it can and does happen that close channel interference causes trouble and it will only get worse as more things use our limited radio bands. One of the problems is cost to make a good receiver for this band even with mass production would cost about £50 a normal car one is about £10 at the most hence the lack of sophistication. The only people that could provide you a list would be one of the breakdown companies, if they record that detail.

I remember the good old days when you did not need a battery to start a car just a quick shove -those were the days, no electric windows, heated seats, electric defrosters on mirrors and 60/45w headlights. The battery was the same size as now poor things.

  octal 21:48 16 Jul 05

Its a known problem. Its not the key its the receiver in the car which is the problem as wiz-king has pointed out.

Mobile phones, although nowhere near 433MHz, no doubt could effect the receiver if it was placed too close to it, due to the large near RF field those things radiate.

The frequency of the key fob system is 433MHz. In the frequency range 420 to 450 MHz you have amateur, MOD, Security and public services transmitters operating, its the worst frequency they could have possibly chosen, considering the car receivers are as wide as a barn door to all those signals.

By the way, the Fylingdales early warning radar system operates between 420 to 450MHz running megawatts of power, yes megawatts its not a typo, and it causes an absolute nightmare with 433MHz devices in the north Yorks area.

  Forum Editor 23:18 16 Jul 05

about cars that suffer and those that don't..........

I drive a Volvo and have never had a problem.

My wife's BMW is unaffected, despite the fact that she works in a clinic with four mobile phone masks on the roof.

My daughter's Ford never has a problem.

My son's Vauxhall Cavalier has been immobilised on three occasions, and he's learned to spot masts and park well clear of them.

  Diemmess 09:37 17 Jul 05

spuds' link was far far better than mine, though the report explained the problem without pointing a finger at any make in particular.

FE has hit the nail right on the head! Half remembered hearsay from a friend who had had trouble, awoke the idea. He drives a middle aged Vauxhall estate and for those who live near it was the old cattle market carpark in Monmouth.

I had a Peugeot 306 and no trouble, but I suspect it had an infra-red Tx Rx system and very short range!

Now exploring the greater mysteries of a new Audi A3, I have possibilites of several new things the key will do, clearly as a UHF system (Thatcham category 1 alarm and immobiliser) whatever that is!

  georgemac © 09:37 17 Jul 05

I have a Honda and have never had this problem - if you do have the problem what is the fix? Do you tow the car away from the mast?

  Diemmess 09:47 17 Jul 05

Tow away till the signal weakens seems to be the thing.

One point in the Telegraph article was that if the car keys were kept too close to a mobile phone which might be active, there were instances where the key itself had to be re-programmed.

  octal 13:40 17 Jul 05

That's highly likely, the little EEPROM can get zapped.

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