Intermittant rf key issue

[Iceman299]

I dropped my key the other day while walking to the car but it opened up fine. 5min journey later it stops working. When i got home it locked after pressing the lock button a fair few times  but then nothing.

Today, i fitted a new battery and it locked/unlocked straight away from our 3rd floor apartment. Got to the car and it doesn't work. Now it keeps randomly working properly until i put the key in the ignition/start the car and then it won't work. After 5mins it'll start working again 

I checked the board for damage but everything seems fine and it does work until i put the key in the ignition which somehow disables it 

Any ideas?

Edit: the fob works without the key. If i put the key into the fob it'll stop working

[pug306driver]

still going round in circles for a key fob test....basic test, kitchen table type test....just to see if the thing outputs a signal..........did you see the small black plastic chip inside the keyfob?? really easy to miss if you don't know its there and what it does.......really insignificant looking black plastic thing....a miniature black brick but oh so important!!

[Iceman299]

still going round in circles for a key fob test....basic test, kitchen table type test....just to see if the thing outputs a signal..........did you see the small black plastic chip inside the keyfob??    really easy to miss if you don't know its there and what it does.......really insignificant looking black plastic thing....a miniature black brick but oh so important!!

Yeah my fob has all the parts and works, but only when it feels like it! 

[powerandtorque]

did you see the small black plastic chip inside the keyfob??    really easy to miss if you don't know its there and what it does.......really insignificant looking black plastic thing....a miniature black brick but oh so important!!

That's the transponder chip for the immobiliser and nothing to do with the RF central locking.

If the transponder chip is missing, the symptoms would be the opposite of this - the central locking would work, but you wouldn't be able to start the engine as the ECU would remain immobilised.

Best guess if the key worked fine before and now doesn't after dropping it, and you've replaced the battery, is that you've cracked a track or joint on the keyfob PCB hence the intermittent nature. 306 keys are normally pretty robust compared to some others, but they're not indestructible.

[Iceman299]

That's what i thought but nothing seems to be visually broken/damaged. I assumed if something was wrong with the circuit, it wouldn't work at all as nothing physically changes with the key between the times it decides to work/not work

[Iceman299]

Ok so basically the fob works if the key blade has been removed. If i push the key back in, it stops working.

The key isn't touching any part of the circuit board or anything else for that matter, so what could be the problem??

[pug306driver]

broken track/make and break contact??  use a magnifying glass to check for breakage.......unit was dropped so suspect something heavyish ??  mounted on the circuit board..........long shot but........  how is battery contact??

[Iceman299]

broken track/make and break contact??  use a magnifying glass to check for breakage.......unit was dropped so suspect something heavyish ??  mounted on the circuit board..........long shot but........  how is battery contact??

It works completely fine when dismantled without issue until i put it all back together. Just the circuit board on it's own works without issue. It's when i start putting it all back together it sometimes stops working. Sometimes stops straight away or after a single successfull attempt it stops.

At times it's when i put the key in to a fully assembled fob it stops working, other times it works fine with the key and one bottom cover but stops when i put the top cover on. 

I just can't see how either a key blade or plastic fob covers would prevent it working