S40 Key Fob Stopped Working
 

My 2008 S40 key fobs no longer. The first stopped working around 2 years ago and the second 2 weeks ago. I have spoken to Volvo who have advised that a diagnostic was required @ 90/hr + VAT. I have been advised that the keys could be reprogrammed to the car by using a series of key fob turns - Is this true?

That technique won't work on yours.
When you say not working do you mean locking function or starting also?
Assuming you've tried the batteries, it's either out of sync with the car or broken, you'll need to reprogram or buy replacement.

Sorry about the late reply but didn't realise that there was one.

The car starts with both fobs and the doors lock/unlock when manually operated from inside the car.

Start with, central locking fuse, corroded connection in cem, central locking unit or broken fob buttons.

CEM Update
 

CEM update required by Volvo
After facing the same issues as everyone on this thread and spending countless hours searching forums to find the answer, I believe this is the only fix. A bit of background first, my main key buttons stopped working and didn’t think much of it as I had a spare, however after a couple of years, that too also stopped working and it become a bit of a challenge locking and unlocking doors. I reached out to Volvo who quoted me a considerable amount of money for a new key as it would need to come from Sweden. Fast forward a few months later, the key finally arrives and I go into Volvo all excited that I’ll finally have a working key, but no, I get a call from them saying that the key works on the ignition but the buttons on the brand new key still don’t work, I explain that I cannot pay for a key that doesn’t work and they respond by telling me that it does in the ignition, after an hour of debating, the master technician arrives and tells me that they will do a CEM update on the vehicle but cannot guarantee this will fix the problem, however I would need to pay for it regardless, I reluctantly agree and they proceed with the update, low and behold, 45 mins later, I’m told the good news and the bad news.

Bad news is the new key buttons still don’t work but starts the vehicle.

Good news is both your old keys are now working fine with no issues.

in the end they decided to send the new key back to Volvo as faulty and only charged for the CEM update which was £45.

Please do let me know if this fixes your problem as it would help a lot of people spending weeks and months searching for the answer.