Car Doesn't Recognize Key

[fishears]

I'm hoping someone can help me figure out what's happening...

 

Every now and then (and getting more regular) when I go to unlock my car in the morning, it won't respond to the unlock button. So, I unlock it with the key and open the door. The alarm sounds. I put the key in the ignition but the alarm continues to sound. Holding the lock button for ten seconds etc does not re-sync the key. I have to pop the bonnet & disconnect the battery then when I reconnect it the key is recognised (I can start the car) and the re-sync procedure works for the remote lock/unlock. I've had it hooked up to Lexia and there are no faults logged.

 

Any ideas?

 

Also, I was just on holiday for a week in Scotland and it didn't do it once up there but the morning after I got home it started doing it again. Could something near my house possibly be affecting it?

[paul.h]

Someone using a mobile phone at the time, phone mast near you, wireless internet, handheld card reader in a shop nearby (this was on the news not too long ago where the frequency was similar to cars) ? Does the spare key work ?

 

I have a few times had the key button not work on our C3 outside our house and in a car park and had to use the key in the door but our car does not have an alarm so once in the ignition no further problems. We had a Picasso with an alarm which also has done similar outside our house but not had to do anything other than put the key in the ignition to stop the alarm. Using the spare keys made no difference. I have not done anything about this.

[fishears]

Someone using a mobile phone at the time, phone mast near you, wireless internet, handheld card reader in a shop nearby (this was on the news not too long ago where the frequency was similar to cars) ? Does the spare key work ?

 

I have a few times had the key button not work on our C3 outside our house and in a car park and had to use the key in the door but our car does not have an alarm so once in the ignition no further problems. We had a Picasso with an alarm which also has done similar outside our house but not had to do anything other than put the key in the ignition to stop the alarm. Using the spare keys made no difference. I have not done anything about this.

 

Thanks for the reply. It's still happening so I've had the alarm switched off - now I don't anger my neighbours. I haven't got a spare key for the car which has never been a problem for me. I'm reluctant to go to the expense of a spare unless I know it WILL cure the problem.

 

Interference (as you say) is at the top of my list of suspects. I can understand an external signal being able to block the key from remotely unlocking the car (if it was present at the same time) but how would that prevent the car from recognizing the key's transponder when in the ignition?

 

Does anyone know if the key has an active, semi-active or a passive transponder in it?