S40 2007 Immobiliser help!

[Dunkmiller]

Hi,
Just had to have the alternator go on my 2007 2.0D S40. Had to get the AA to take me to the nearest garage (independent), and they've replaced the alternator. However, they've now had the car for 3 days as they can't get it to start because the immobiliser won't recognise either of my keys now. They've tried the lock and unlock 5 times with the key method that's been recommended on these forums before, but that didn't work. I'm hoping/assuming that there's a simple answer to how to get over this, and I'm hoping someone on hear can help out.
Any advice gratefully received,
Duncan

[spokoluzik]

Your ecm lost immo synchronisation. Can make it back working if you post ecm and cem to me.
Regards
Lukas

[Dunkmiller]

Thanks for the reply, although I'm afraid I'm not sure exactly what you mean. If you could tell me what the ecm and cem are, and how I find them, that would help a lot,
Thanks again,
Duncan

[spokoluzik]

ECM- engine control module located under your left front wing.
Removal video https://www.youtube.com/watch?v=WSN1AzUDT28
CEM- central electronic module located under glovebox on passenger side.
To remove cem you need to push 2 rivets and undo 2 kind of screws. Then undo all plugs and you're done.